tabWindow() is null

I am trying to run a function that is inside a tabbar content page usiing tabWindow(tab_id) and I get a  ‘tabbar.tabWindow(…)’ is null or not an object error message. 

I have tried…

var f = tabWindow(‘t3’);


and several other variations and always get the message above.   The tabbar IS named tabbar and the tabbar works fine.

Do you use iframe-based mode ?

If yes, please, check that you call function when the content of the iframe is already loaded. Possibly you need to set some timeout. tabWindow returns the window object of the page inside iframe.

window_object = tabbar.tabWindow(tabId);