transformation problem

[satya lakshmi]

hi
iam facing problem with ligation of a cloned product.my vector and
insert both are PshA1/Bstap1 digested. but when i transfrom my ligated
product i am not getting any colonies while the ligated product shows
a band above the vector running like a relaxed circular form when
compared with the undigested.
can anyone help me as aim unable to understand what could be the
possible problem?
satya