I am using iSE6 to test a opencores project. All the files are in good order, however, when the files were added to the project, there was a "eth_registers" module which can not merge into the tree in the top project, though the instantiation and other syntax are correct. ISE indicates a missing module for "eth_registers", however the file was included in un-used file section of the project. There were no `ifdef sattement to exclude this module.
Thanks