Antenna / Aerial Question

Hi all,

I currently have the factory fitted radio head unit and FM reception is perfect.

I am installing a CarPC and I have an USB FM stick for the CarPC FM radio. I bought myself an MCX to Facra cable in order to connect the USB FM stick to the existing factory fitted Car Aerial. However, the signal strength meter shows that the signal is worse when the cable is connected as opposed to when it's just held up in the air - which seems to make no sense.

If I re-connect the Facra connector back into the existing radio, the signal is again perfect. Is there any reason why the new FM stick should not work, linking up to the existing aerial ?


C