How to Use micSendString?

I use this :
dim R as integer
R=micSendString("OPEN c:\abc.mid TYPE sequencer alias abc", 0&, 0, 0) or
R=micSendString("OPEN c:\abc.wav TYPE waveaudio alias abc", 0&, 0, 0) then right,but I use like this then wrong:
dim strCmd as string
strcmd="OPEN " & filename & " TYPE " & micType * " alias abc "
R=micSendString(strCmd, 0&, 0, 0 ) is no mid or Cd or Wav Play,why?