NSTextField returning null when it should not

FROM : Brian Weitzner
DATE : Fri Aug 11 19:09:47 2006

Hi all,
      I have an action that is triggered when a button is clicked.  It 
takes the string in an NSTextField and formats it so it can be passed 
to another method.  A matrix of radio buttons is used to determine 
what text field the string should be taken from.  Here's the code:

else if([searchMatrix selectedTag] == 1){

   NSLog(@"the input in the text field is: %@", [pdb stringValue]);
   if([[pdb stringValue] length] != 0){
       <format the string>
     }
}


So when I look at the debugger console while my app is running and I 
put something in the text field and click the button, it works as 
intended... the first time.  After the first time the button is 
clicked, if I click it again, the console displays my log displays 
"2006-08-11 12:05:39.960 ProtBuD[3988:117] the input in the text field 
is: (null)"  The input is clearly not null.  Any ideas about why this 
might happen?  Thanks.

--
Brian Weitzner