Problem communicating outer componnents such as camera

Hello everybody

I'm connecting to serial port COM3 ('s=serial(com3)') in order to activate Thorlabs filter wheel (FL102c).

When I do it for the first time everything works fine but when I try to reopen the connection (I have closed it before with "fclose(s)" function I recieve message that the port is unavailable.

Additionaly when I connect to a camera (AVT-GX-1920) I can see through the camera but if I try to restart the camera again I get that there are multiple cameras connected error.

It seems that the camera and the filter wheel are somehow still in the matlab memory.

I'm using (R2011a) version.

Thank you for all your help

Ariel