why doesn't this callback update the adapter?

gistfile1.txt

def callback4(instance):

    app = App.get_running_app()
    if instance.text in app.l.ids['missing'].adapter.data and instance.is_selected == False:
        newlist = app.l.ids['missing'].adapter.data
        newlist.remove(instance.text)
        #app.l.ids['missing'].adapter = SimpleListAdapter(data= newlist, cls= ListItemLabel)
        print 'newlist is:  ', newlist

the list logic is working, but the adapter assignment fails with this error: Exception: list adapter: data must be a tuple or list 

the data arg IS a list! here is the console output:

newlist is:   [u'Alexy, Dorthy', u'Altonen, Colin', u'Amaral, Ramon', u'Arenburg, Margot', u'Argenti, Kathie', u'Arguin, Leif', u'Armout, Isabell', u'Asberry, Kurtis', u'Balandran, Socorro', u'Bandyk, Georgette', u'Barcelona, Bette', u'Baucher, Efren', u'Baumann, Rolando', u'Behen, Cyril', u'Bellendir, Eduardo', u'Bellerdine, Lyndon', u'Benthin, Ike', u'Beresnyak, Kathleen', u'Bernasconi, Patty', u'Betance, Norman', u'Biasotti, Alyssa', u'Bickel, Raphael', u'Bigg, Laurie', u'Blumenthal, Elvira', u'Bonnet, Sean', u'Bordwell, Samantha', u'Bottella, Bridget', u'Bousman, Marquita', u'Bowditch, Jannie', u'Braithwaite, Robt', u'Brantz, Lane', u'Brevard, Davis', u'Bridgeman, Kylie', u'Brining, Burton', u'Brockert, Travis', u'Brodtmann, Pamala', u'Bruckman, Candice', u'Brumet, Rebeca', u'Bruni, Kenya', u'Brzostowski, Vivian', u'Burigsay, Diann', u'Caetano, Naomi', u'Cantu, Audra', u'Caraway, Lynda', u'Carlan, Hans', u'Carleton, Melinda', u'Cassa, Hilario', u'Catino, Boris', u'Cervantsz, Adela', u'Chipley, John', u'Christophel, Robyn', u'Cieloszyk, Gaston', u'Cintora, Henrietta', u'Circelli, Sharlene', u'Clemmens, Petra', u'Coger, Annabelle', u'Constantineau, Wilmer', u'Cosby, Madonna', u'Courrege, Tyree', u'Cowan, Corinne', u'Cowley, Billie', u'Crotts, Rubin', u'Cuneo, Coleman', u'Cuttitta, Dwain', u'Dagenais, Elmo', u'Daquino, Dollie', u'Daulton, Rosalyn', u'Declue, Tamara', u'Derouen, Lashonda', u'Detillier, Sherwood', u'Dienhart, Manuel', u'Dragaj, Justina', u'Duffy, Oma', u'Dummermuth, Rene', u'Earman, Marianne', u'Edberg, Waldo', u'Edd, Kevin', u'Ehn, Gracie', u'Ekstrom, Millicent', u'Emayo, Jacklyn', u'Enote, Lashonda', u'Erlebach, Jade', u'Erlewine, Teri', u'Ettel, Vince', u'Evertt, Kerry', u'Facio, Hannah', u'Fifield, Rosemarie', u'Folz, Marla', u'Fontanella, Wes', u'Fontanilla, Athena', u'Forness, Geri', u'Fostervold, Danette', u'Friesner, Barton', u'Gabouer, Elmo', u'Galas, Jarvis', u'Ganguli, Kay', u'Gansen, Randal', u'Garnette, Maryann', u'Garrigus, Lana', u'Gartenmayer, Judy', u'Gaulden, Marion', u'Gawron, Jacinto', u'Geimer, Gayla', u'Gidley, Wilfredo', u'Gillispie, Allyson', u'Gleave, Rich', u'Gompf, Ed', u'Gould, Felipe', u'Graen, Sandra', u'Granberry, Valentine', u'Greenly, Naomi', u'Griffeth, Rena', u'Groden, Shelley', u'Gum, Jasmin', u'Haakinson, Sue', u'Hammeren, Marlene', u'Harnar, Mitchel', u'Hasselvander, Bradly', u'Hasty, Lashawn', u'Haza, Jude', u'Hedglin, Brice', u'Heideman, Davis', u'Helmich, Delphine', u'Hindley, Barbara', u'Holloran, Sheila', u'Humes, Reginald', u'Hwang, Mari', u'Hybarger, Lina', u'Iberg, Helene', u'Ihenyen, Mitzi', u'Inafuku, Deshawn', u'Iurato, Lucien', u'Ivrin, Meredith', u'Jakuboski, Nelly', u'Javens, Lee', u'Jerko, Roseann', u'Jurasin, Mack', u'Kaewprasert, Maynard', u'Karczewski, Berta', u'Keels, Lana', u'Ken, Karla', u'Kennemur, Rosalia', u'Kenzie, Jarrett', u'Kesich, Savannah', u'Kinlaw, Carolina', u'Kirklin, Kennith', u'Kivel, Judi', u'Kluemper, Randall', u'Knightly, Bridget', u'Knust, Tiffany', u'Kokoska, Yvette', u'Kolm, Armando', u'Kornbau, Margarito', u'Kosicki, Gisela', u'Krenzke, Rosalind', u'Krigger, Rosalie', u'Krisman, Carol', u'Kruss, Tricia', u'Kuhle, Rudy', u'Kuhlman, Milton', u'Kunde, Fred', u'Laboy, Bernard', u'Lampi, Jeremy', u'Lanfear, Conrad', u'Langner, Sophie', u'Larrison, Rachel', u'Leboeuf, Callie', u'Lendor, Lora', u'Lewallen, Vanessa', u'Lijewski, Garfield', u'Lindauer, Kyle', u'Lingbeek, Valeria', u'Linnan, Amos', u'Lino, Tia', u'Loose, Claudio', u'Luby, Bertie', u'Lunan, Reginald', u'Maddalena, Dwayne', u'Maggs, Marcelino', u'Mahone, Felipe', u'Marksberry, Mac', u'Marschke, Son', u'Marsell, Neva', u'Marso, Bess', u'Mascall, Alejandro', u'Matrisciano, Doug', u'Maurizio, Mary', u'Maury, Mariano', u'Mcaulay, Saundra', u'Mcbay, Kurtis', u'Mccamey, Cary', u'Mccleary, Antione', u'Mcdonnell, Mandy', u'Mcintee, Mamie', u'Mckibben, Lamar', u'Mcshaw, Fabian', u'Mcsorley, Viola', u'Menedez, Curt', u'Merlin, Darren', u'Miklas, Chad', u'Minaai, Johnie', u'Mockus, Zackary', u'Monroy, Maurine', u'Mountjoy, Alissa', u'Moyerman, Claire', u'Muhl, Logan', u'Neiss, Darrin', u'Neundorfer, Shanna', u'Nicolaus, Cathryn', u'Nimmer, Terrance', u'Nolau, Gale', u'Numkena, Shanna', u'Oborne, Val', u'Oroark, Enrique', u'Overfelt, Carmel', u'Padley, Rebekah', u'Paker, Kristine', u'Papik, Armando', u'Parbol, Avery', u'Pennigton, Alva', u'Persson, Kris', u'Phoenix, Nathanial', u'Pillitteri, Dollie', u'Pindell, Sal', u'Pliner, Luella', u'Pou, Valerie', u'Prudente, Edgardo', u'Pyfrom, Evan', u'Rabeck, Alene', u'Radman, Veronica', u'Ransonet, Keisha', u'Reich, Winnie', u'Reiniger, Caitlin', u'Reisenauer, Reina', u'Retort, Bridgett', u'Riedl, Felecia', u'Rocheford, Haley', u'Rodda, Terrell', u'Roudabush, Cruz', u'Saddat, Melody', u'Salera, Pierre', u'Samrah, Devon', u'Sandrock, Rosanna', u'Sarchett, Concetta', u'Saulsberry, Lynn', u'Scarpa, Gil', u'Schaffter, Janet', u'Schattner, Mitch', u'Schermerhorn, Angelique', u'Schkade, Benjamin', u'Schorr, Steve', u'Schwallie, Walton', u'Schwantd, Allan', u'Schwartzwalde, Tammie', u'Scroggie, Modesto', u'Scronce, Lona', u'Seahorn, Eva', u'Seid, Roger', u'Sharper, Cristina', u'Sheffler, Ofelia', u'Sherretts, Donald', u'Simone, Roman', u'Sirbaugh, Carla', u'Sisk, Waldo', u'Sisofo, Sheryl', u'Smiler, Marisa', u'Soo, Francis', u'Speach, Warren', u'Speegle, Denise', u'Stanzak, Kris', u'Steese, Fannie', u'Stika, Krystle', u'Streu, Reggie', u'Suddeth, Pilar', u'Suermann, Helena', u'Sule, Mellissa', u'Sulikowski, Zane', u'Sutch, Eldon', u'Sweem, Dorothea', u'Teston, Devon', u'Thierauf, Antony', u'Tinnes, Billie', u'Tivis, Heriberto', u'Tork, Darrel', u'Tout, Trey', u'Trybus, Tami', u'Tsang, Guillermo', u'Vaidya, Brent', u'Vanalphen, Heath', u'Vanderzwaag, Mara', u'Varrato, Kelli', u'Villaescusa, Tori', u'Voll, Lottie', u'Wadlinger, Junior', u'Waldall, Jonathon', u'Weeden, Mabel', u'Whittley, Lyman', u'Whyman, Maryanne', u'Wice, Eliseo', u'Willardson, Florine', u'Wilshire, Nadia', u'Windle, Helga', u'Woldridge, Marisa', u'Worlds, Trudy', u'Youtsey, Lynda', u'Zackery, Isaac', u'Zanders, Fran', u'Zarzycki, Jimmie', u'Zeolla, Ike', u'Ziesemer, Malissa', u'Zombo, Karen', u'Zortman, Ruthie']