Carlton
I had a similar problem controlling a Zune adapter. I was using the supplied IR blaster with the Pronto RFX 6500. It didn't even work. BUT, if I used the same blaster through a Xantech IR repeater, and the Pronto set for IR, it did! Go figure. What cured the problem was to use a Xantech 282 IR blaster. DON"T ask me why!! It works great now, at long distances of 75ft, through two floors! I'm not sure a RFX6000 will work quite that well, but you never know. I have found the RFX6500 is far more reliable. Also, found the optimal setting for most any IR code through the RFX6500 is .3 duration.
Let us know what you find.
Dan