problem with appending to a list, possibly mysqldb related

[John Salerno]

Here's the code:

class MyFrame(wx.Frame):

     def __init__(self):
         wx.Frame.__init__(self, None, wx.ID_ANY)
         panel = wx.Panel(self)
         dbconn = self.connect_db()
         dbconn.execute("select namefirst, namelast from master")
         bb_players = []

         for x in dbconn.fetchall():
             bb_players.append(' '.join(x))

         cb = PromptingComboBox(panel, 'Choose A Player', 
choices=bb_players, style=wx.CB_SORT)

     def connect_db(self):
         connection = MySQLdb.connect('localhost', 'john', '*******',
                                      'bbdatabank')
         return connection.cursor()


The error seems to be in the for loop. I get this:

Traceback (most recent call last):
   File "C:\Python24\myscripts\bbdata_access\bbdata.py", line 71, in 
-toplevel-
     app = MyApp(False)
   File "C:\Python24\Lib\site-packages\wx-2.6-msw-ansi\wx\_core.py", 
line 7700, in __init__
     self._BootstrapApp()
   File "C:\Python24\Lib\site-packages\wx-2.6-msw-ansi\wx\_core.py", 
line 7352, in _BootstrapApp
     return _core_.PyApp__BootstrapApp(*args, **kwargs)
   File "C:\Python24\myscripts\bbdata_access\bbdata.py", line 64, in OnInit
     frame = MyFrame()
   File "C:\Python24\myscripts\bbdata_access\bbdata.py", line 15, in 
__init__
     name = ' '.join(x)
TypeError: sequence item 0: expected string, NoneType found
 >>>

I know the method of joining the items in the tuple and appending to a 
list work, so I figure it has something to do with either mysqldb, or 
maybe the PromptingComboBox I am using.

Hope someone can spot the problem!

Thanks,
John