'Sources not found' message in intelliJ IDE on clicking any Sikuli specific class

IDE - intelliJ
SikuliX setup using sikulixsetup-1.1.jar

When I click on any Sikuli specific class on intelliJ IDE, like 'Screen', 'Pattern', 'Region'..., the corresponding class definition is displayed on a separate Tab as expected.
However on the top of the class definition, the message 'Sources not found' is displayed. Also, a link 'Attach Sources' is displayed. When I click on the 'Attach Sources' link, the path is correctly specified as 'C:\SikuliX\sikulixapi.jar'.
So, I'm now confused as to why I've this 'Sources not found' message appearing, irrespective of the correct source path specified.

I had got the same sort of 'Source not found' error on Eclipse too. However after installing Java Decompiler plugin, the error went away in Eclipse :-). I tried to do the same on intelliJ - however, it didn't resolve my issue :-(

Will be grateful if anyone could help.

Thank you.

Regards,
Sen