Co-transformation - (Mar/09/2013 )

hello, i already done the transformation of my insert into new vector in dh5a host and extracted into a plasmid (CYP3A4-pcWori-dh5a plasmid). then my lecturer said that i need to perform a co-transformation in oxy-reductase vector (pCYAC-OXR) before express the protein, so can i just do the co-transformation of CYP3A4-pcWori-dh5a (Amp resistant) and pCYAC-OXR ( chloramphenicol resistant) plasmid like doing standard transformation? or there have different methods.
now, i just do the standard transformation by put in 25ng of CYP3A4-pcWori-dh5a+ 25ng pCYAC-OXR into dh5a competent cell and streak on chloramphenicol 100ug/ul plate..the result is negative.

Never heard of cotransformation. What is its purpose. You do transformation in order to obtain pure colonies which only carry one type of plasmid

thank you for your opinion, the purpose of co-transformation is to insert another plasmid into a host which is will help my vector-insert to be expressed well. Right now, i already got it by performing standard transformation with combination of two plasmid in less than 10% of competent cell volume..thank you very much