Puzzling copybook behaviour in VC for Eclipse

The directory hierarchy on the AIX machine that I am using has been set up with a development user containing a 'sources' and a 'copies' directory, with .cbl in one and .cpy in the other.

Setting this up as a remote project in VC, I have created a symlink to the 'copies' directory in the 'sources' directory and mapped the project to the 'sources' directory. The copybook paths include the 'copies' directory, which is checked. The 'copies' directory shows up under the project, and if I go into it, I can load the copybooks into the editor.

The copybook files are all named in lower case and the names are in quotes.

If I "build project", all the copy statements fail "unknown copybook". However, if I open a program file in the editor and right-click on a copybook name and select "Open Copybook", the copybook opens in the editor.

I can work round this by putting the copybooks into the 'sources' directory.

I'm sure I've had this exact setup working properly a little while back, before I had to put VC on the back burner. It's bound to be something I've missed - has anyone got any suggestions?