@dkolok said:

I have the same problem. It worked great in 8 but gives that error message in Sketchup Make. A made a cube turned it into a group, made a second cube turned it into a group. the cubes overlap by about 50% then I select the two groups. A window pops up and says "OSCOOLEAN needs UPDATE: OSCoolean is a beta version(Sep 2010) for Google Sketchup Version 8!
then you click on OK and get nothing.

Same error here