Switching between NSTabView

[kikko088]

Hi at all, I'm new of this forum and of mac programming, I have a little question, I create a new doc-based core data project, on myDocument.xib I put a NSTabView, the view of each itam have a class. For each tabitem view I put a button for change the tab from myDocument.m class I use

[myDoc selectNextTabViewItem:nil];

and all work perfectly, if I try to change the tab from one of the view tab nothing to do...I use this code

myDocument *myDoc = [[myDocument alloc] init];
[myDoc.tabView selectNextTabViewItem:nil];

where is the errora for you?
thank you

kikko088