ligation of bluntet fragments

[Trygve Meum Eliassen]

I'm having difficulties cloning a PvuII-SmaI fragment (i.e blunt in both
ends) into a vector cut with EcoRV (blunt) and AatII (3' overhang). The 
sticky end has been bluntet with T4 DNA polymerase (NEB). I figure the 
problem is inefficient blunting and/or ligation. Has anyone got any 
suggestions as to how I might improve any of these methods? I'm mostly
following the instructions in the NEB catalogue.

Thanks in advance. thomas.moen at biotek.uio.no