I would check the text in Details::Status and see if maybe it is "Partners" instead of "Partner". An added space might also be the culprit.
Thank you very much for the reply. While the singular -> plural relationship is potentially confusing, it is definitely not the cause of the problem (see my Goofball experiment), and your idea to check for spurious spaces was a very good one. Alas, no rogue spaces anywhere.
I did create a workaround. As I mentioned, instead of going to the Partners tab, the script takes me to the default tab. So seeing how the other four work fine, I just changed the default tab to be Partners, and now when it fails, it dumps me where I want to be in the first place.
Still no idea why it fails, but my bandaid seems to be holding...
Your "goofball experiment" checked the OBJECT NAME, but as far as I could tell, did not check the text in your FIELD. If the problem lies with the data in the field, changing the object name and specifying the new name in your script will not check that detail.
For my Goofball experiment, I changed the data in the Status field to Goofball, renamed the Tab to Goofball, and updated lines 3 and 4 in the code above.
To state what is probably very obvious to you, the same exact text has to appear in three places, the object name box, the quoted text in the if step and in the set variable step. One letter difference in any of those three places will keep this script from working.
You might compare your file to this one where I tested some of the concepts covered in this thread: https://dl.dropboxusercontent.com/u/78737945/TabControlTest.fmp12 In the test file, you can click the radio button field to trip a script trigger that performs the test script and it then pops the selected tab to the front.
Do you have any script triggers set on either the tab control or fields inside the Partners tab panel? If a script trigger is being tripped by your script, that might explain what you are getting this issue and this will be the case no matter what names you use.
You might also try, as a test, creating a brand new layout put a brand new tab control on it with the correct tab panels and object names and see if your script works on that test layout. That could identify an issue with your layout either an interfering script trigger or even corruption of the layout itself.