transformation (electroporation) - (Aug/11/2007 )

When I do transformation (electroporation, Bio-rad), sometimes it says the puls is not sucessful (I forget the sentence on the screen, but I think something like this). So I do not know what happen there......

anything else? Horrible electric spark? Arching between electrode? Is the whole lab experiencing the same problem? Could the machine be in need for servicing?

May be you are using PEG in the ligation Buffer or have high salt concentration in your sample. I remember T4 Ligase From invitrogen have PEG and this do interference with electroporation, try to precipitate your DNA before transformation to remove salts and PEG from ligation reaction, before electrotransformation.