Xcode - documentation: File not found!

[admin]

If i call the documentation via Alt+Doubleclick or normal by the menu there appears a message with the title: "File not found! This request file was not found in any documentation set"

But if i click okay, the information about the thing I searched comes normally..

What is that error about? How can i fix that? its really bothering me because everytime i hit a link in the documentation this message appeares again.

Thanks,

Rob