weird blunt-sticky ligation case - (Jul/02/2006 )

HI everyone, I have great difficulty in one ligation experiment recently. I have almost not obained any recombinant transfromant in my LB plate for one month. Negative control (only linear vector and insert have 10 more or less colonies, however, ligation transformation plate grew 1 colony)Please analyze the weird case. Any suggetion is appreciated.

May b too much XhoI used with vector digestion, could chew up the ends.

Also the total amount of DNA used for ligation seems too much.