[closed] multi monorecording problems

[foo]

Hi, I am using audacity 1.3.4 on ubuntu 8.04.
I setted the audio i/o to mono, in the preference pannel.
I recorded a voice track and saved the project.
what I would like now is to open the project and record a new track or continue to
record the old track; the problem is that I get an error when I try to do
this...
I put the audio I/O to stereo and all worked fine, I could record new tracks in stereo but I would like register in mono...
Is this Behaviour a bug of audacity!?

[Edited 27/4/2009 19.18]

Ok, I found how to resolve the problem.

I have gone in: Edit -> Preferences -> Audio I/O

in the box: "Recording" I have changed the device from OSS: /dev/dsp to ALSA: default.
I have done the same for the play back device...
Now all working...

I don't know what was the problem... if some one can explain me what happened is well came...

any way now all working correctly!!!