“If you have installed Active Sky Next (full or trial) for FSX and want to use FSGRW as well, you need to have installed FSUIPC from version 4.925. Download it from the link at our website at http://www.fsim.net
Earlier versions will result in FSGRW failing to deliver correct upper air winds. Never use both weather programs at the same time.
Thanks to Pete and Damian to sort that out.”
FSUIPC 4.925 is available directly from Pete Dowson’s modules thread here at the simFlight forums.