I am having a peculiar problem when operating IO-117 (Greencube) When on an Ascending pass (South to Borth) I can hear the satellite very well but cannot access the digipeater! It makes no difference whether it is at 5 degrees or 50 degrees and whether the satellite is coming up from 180 or 030 degrees. I have no obstructions throughout these passes ! However when on a Descending pass (North to South) I can hear it as well as access the digipeater without any problems. I am running a IC9700 with a 14 element yagi horizontally polarized. I have 75 watts available and using the built in sound card from the IC9700 and the IO-117 modem and digi software from UZ7HO.  Is there any reasonable explanation or is anyone else experiencing this problem?  It has been frustrating  to be able to see the DX stations and not be able to work them.  Thanks for any help or suggestions on this matter.

JACK  KC7MG