Parameter Forwarding

Hi,
I want to shorten an affiliate link with the tracking id.
The affiliate link is as follow http://affilaitesite.com/?tid=trackingid

The shorten link http://sho.rt/abcd redirected to http://affilaitesite.com/?tid=

While using Parameter Forwarding,
http://sho.rt/abcd?trackingid must be redirected to http://affilaitesite.com/?tid=trackingid

But the link is redirect to http://affilaitesite.com/?tid=&trackingid,
Character “&” is added in tracking id, Only the alphabets and numbers are accepted as tracking ID.

Is there anyway, the parameter forwarding function works without the “&”?

Thanks.