Unable to open COM port


I have configured a Digiconnect ME device as a
RealPort device. Everythings seems ok. On my
PC (Win XP SP2), I see a “Digit connect Port” COM20.

When I try to open a connection to this device
through the Hyperterminal, it tells me “Error, unable
to open COM port, check your settings”.

Does anyone have any idea why ?