A user reports:
I have noticed interferance between ClipMate and As-U-Type by Fanix Software, when on ClipMate does not paste the item you have selected. If I disable As-U-Type's 'use multiple clipboards' then ClipMate works. I hope this helps.
Thanks to Russ for providing this tip.
Generally, if a program has its own multiple-clipboard support, it's best to turn it off when working with ClipMate