Did you get anywhere with this?
I had this issue after install. you'll run into it w/ most 'tempo based' fx.
i'm dont have sonar up so this may be off but
Go to the plugin manager, highlight/choose LFO tool from the list of installed/registered VST plugins and hit 'plugin properties' (i think?) make sure the box with the something something ...'tempo based' is checked.
The other issue i had was on the 64 bit version of sonar 8.5 only the 64 bit version of this plug in would work. hope it helps.