ID:178002 Could not find reference clock network from <name> to <name>

CAUSE: The Fitter could not place the specified blocks in such a way that reference clock network connectivity requirements between these blocks could be satisfied. The reference clock networks span each side of the device. This message may be displayed because one or more of the specified blocks have location or region constraints that make it impossible to satisfy the reference clock network requirement.

ACTION: If you made a location assignment to the specified blocks, remove the assignment if possible. If this does not result in a successful fit, compile the design targeting a larger device.