Failure of ligation - (Mar/20/2001 )
Did you set up a dummy test, with the competent cell line you are using, to prove that the cells are competent? Did you run a gel and prove your DNA both insert and vector is there? Did you make sure that the buffer conditions were correct during the ligation? Ph was what it should be?
I've had problems ligating before. I purfied digested DNA, and was lazy, did not run it on a gel to confirm it was fully digested, and then ligated. Nothing was there. The buffers I used for purifcation of digested DNA was off.