Linker interferes w Transformation?

[Richard Near]

I am simply trying to insert a linker (about 10 nt, phosphorylated)
into a plasmid in order to add a new restriction site.  I have
linearized the plasmid, filled in ends with klenow and then 
ligated (about 3 ug linker) the linker into the plamid overnite
at 12 C.  Upon transformation of DH5a (Ca competent) and selection
on LB amp plates I got no colonies.  NOW THE QUESTION: SINCE I
DID NOT REMOVE EXCESS LINKERS AFTER LIGATION, COULD THEY 
INTERFERE WITH THE TRANSFORMATION?

thanx
rick
rocket1 at bu.edu