The following fatal error occurred during directed packing:
"Running directed packing...
FATAL_ERROR:Pack:pksbamergeset.c:573:188.8.131.52 - Expected a valid component
type. Got "" instead. Process will terminate. To resolve this error,
please consult the Answers Database and other online resources at
http://support.xilinx.com. If you need further assistance, please open a
Webcase by clicking on the "WebCase" link at http://support.xilinx.com"
This issue is caused by packing an SRL together with the MUXF5 it is driving. This problem was fixed in 7.1i SP3.