Varispead not working on sidechain compression

I've increased the tempo of my track using varispead and have sidechained the compression on some of the instruments to the kick, however the side chained compression seems to be ignoring the varispeed and is compressing the instruments according to the slower kick pattern, meaning I don't get the effect in the new tempo (basically sounds like its compressing the instruments randomly but from the pattern it does seem like the kick pattern just a lot slow...any ideas?