Harvesting cells - (Mar/13/2014 )

That's a perfectly standard transfection procedure.  Have you checked that the plasmids are intact and did you isolate the plasmids using a commercial kit (which one)? A260:A280 ratios? 

Try adding the DNA and turbofectin to a smaller volume of medium, maybe about 50 ul/well.

Yes, I checked the plasmids by agarose gel electrophoresis and they were intact. Also the ratio was ok. I am repeating the same experiment next week. I will try as you have suggested. More what's the best confluence that you would like to recommend for seeding of cells.

Thank you very much

Anywhere between 50 and 70% should be fine.