weird Cubase SL and MIDI problem?

[mince]

i've been using reason for a long time but now i switched to Cubase SL. Everything is fine except the MIDI recording. I have a Roland A90 controller, and also using a Roland UM4 USB MIDI interface. I connected the MIDI Out of the controller to the MIDI In of the interface and selected the input in Cubase to record. The rec button is activated and I receive signals in both MIDI activity and level meter. When I start recording there is no data flow into the program. If anyone can help me solve this problem, I will be very happy. Thank you very much