This question doesn't belong in the "JBoss Cache" forum. It should been posted in "JBoss AS".
If what you want is to have a transaction that is started in one JBoss (A) to be "continuing" into the other JBoss AS (B) you need JTS. By default only JTA is enabled so B will never know about the transaction started in A and will start a new one that terminates when the call returns to A.
Thanks Anders. I will look into JTS. Btw, thread moved to JBossAS.