Carlos. I'm afraid, I've some problem to attach BV2 cells. I've no a 100% of attached cells but I noticed that the standard polylysin protocol works best if the plate are treated the day before of the cells seeding.
Hey! I used poly D lysine (same concentrations mentioned above but prepared from powder) recently -for different cells though. I optimized protocol for my cells to plate on cover slips/glass slides . What I did was:
Washed slides with PBS first then treated plates with poly D lysine - left with hood on for 24 hrs. This worked better than normal incubating conditions (don't ask me why ).
Then washed with PBS again.
Ahh I forgot imp step, before sterilizing slides/c slips, I treated plates/slides with conc nitric acid for 15-20 hrs to etch the glass so they adhered better. After sterilizing coated as mentioned above!
Try etching glass and prepare coated slides fresh (like before a day or so)- it might work!