Cym Akaka falls (dayanum x tracyanum) culture question

[W Stender]

Hello all, I am having problems with a warm growing Cym called Akaka Falls (dayanum x tracyanum). When I bought it 2 years ago from the Duffins in Phily, Pa it was in horrible need of repotting. It was a real chore to repot. The Duffins suggested a cymbidium mix by Waldor orchids that is very peaty and moisture rententive (consists of two grades of firbark, peatmoss, and sponge rock). They love it. I have used it on all my Cyms and so far seem OK. Unfortunatley I have had problems with this Cym since I repotted it. it gets lots of new shooots that grow to about 6" to 10" long, and then they literally rot off at the base and pull out of their socket. I do not know what I am doing wrong, but I am considering repotting with a less water rententive mix. Does anyone have experience or suggestions on the culture of this orchid or either of the parents? Hurry up with answers before I kill it!