Following are some common issues and known causes, and the ways to work around or resolve the issues:
1) When attempting to add the example design source files to the Project Navigator project, the "Adding Source Files..." dialog box shows a red X with the message "<file name> is already in the project, it cannot be added again. If the file does not appear in as expected in the design hierarchy, you may need to change the view association in the Files panel."
The file cannot be seen in the hierarchy view or on the Files panel.
This can occur if the core has been added to the project and the example design files are included in the sub-project associated with the core (<core name>.xise in the ipcore_dir directory).
To work around this issue, you can remove the core from the project, add the example files, and then re-add the core to the project.
2) Implementing or translating the design results in a message similar to the following:
"ERROR:NgdBuild:604 - logical bloc 'trimac_locallink/trimac_block/trimac_core' with type 'mytemac' could not be resolved. A pin name misspelling can cause this, a missing edif or ngc file, or the misspelling of a type name. Symbol 'mytemac' is not supported in target 'virtex5'"
This error occurs because the core (in this case the TEMAC block) is a separate netlist (or set of netlists) that gets generated and is not contained in the example design files.
To resolve this issue, add the <core name>.xco file to the ISE project.Adding the XCO file, adds the core sub-project and all of the files associated with the core to the ISE project.
Alternatively,you could add all of the files associated with the IP core manually (e.g., add the "core.ngc", "core.ucf" or "core.v/hd" files from the ipcore_dir and ipcore_dir\<core name>\implement directory).The limitation of this option is knowing which files need to be added.