Building with Xcode 3.1 fails to find ibplugins

FROM : Christiaan Hofman
DATE : Sat May 24 19:24:43 2008

I'm having trouble building a project using PDFKit in an .xib file. 
When I try to build I'm getting this ibtool error:

Internal Error:
   Description: Unable to resolve plug-in dependency for "MyDocument.xib".
   Recovery Suggestion: Locate the com.apple.pdfkit.ibplugin Interface 
Builder plug-in to continue opening this document. Consider using the 
--plugin option or Interface Builder's plug-in preferences to resolve 
this dependency.

I should note that IB 3.1 does have the PDFKitIBPluginLibrary set in 
it's plugin preferences (I think it even is there by default). So 
the .xib file should have this dependency declared, or ibtool should 
be able to resolve it from the IB preferences. Is this a (known) bug?

Thanks,
Christiaan