No RNAP but beta-galactosidase

[hanna jangg]

Dear Colleagues,
I am currently trying to overexpress RNAP(B.subtilis) in E.coli strain B834 (DE3) pLysS. 
My plasmid DNA(pNG219) contains three of RNAP subunit genes which are downstream of T7 promoter. 
I do fresh transformation but still get very low amount of RNAP(with 9x his-tag). 
Instead of RNAP but Beta-galactosidase is overexpressed. Does anybody have this problem?
 
I followed protocol for pNG219 that has shown below.
http://www.ncbi.nlm.nih.gov/pubmed/18289874 
 
Thanks,
 
Hun