Cubase LE 5 Lexicon Alpha

Hi, i have a little problem. I installed cubase le 5 and drivers for lexicon alpha. In cubase i have chose Alpha ASIO and i have heard the sound from cubase when i put audio track and there was a singal(low signal but still) from intput guitar. Second time when i have opened cubase nothing worked. Intup or output. When i change ASIO driver to ASIO DirectX Full Duplex i can hear sound from audio in cubase but i can;'t hear any input signal.