FCK Editor Plugins and DotNetNuke

Question

I have a plugin I developed for FCK for our management site - its not a hugly complicated one but it was working untill we upgraded our site to DNN 5.2.2

Now the functionality of the plugin appears to be okay (at least it has the correct info in the dialog box) but the 'okay' button does not appear at all - other dialogs appear to not be affected.

In the script for the dialog I have this. In all the other plugins I look at this works and seems to be the way to do it. I need some help to try and fix this please.

window.onload = function ()
{
// First of all, translate the dialog box texts
oEditor.FCKLanguageManager.TranslatePage( document ) ;

LoadSelected() ;

// Show the "Ok" button.
window.parent.SetOkButton( true ) ; 
}