Does anyone have experience solving problems with LR reaction?

Hi, My colleague is trying to do the LR reaction to move an artificial miRNA from the entry vector to the destination vector. Both vectors have the same antibiotic resistance gene. He has tried:

1) Linearize the entry vector and setup LR reaction with destination
vector ( pGWB2)
2) Linearize both entry and destination vector before LR reaction
3) incubated over night
4) Linearized destination vector using the recommended restriction
enzyme and then set up LR reaction

Any help here would be greatly appreciated because we are stuck and we need to get this done very badly. Sarah