HMGCoA Reductase

[redmerlin]

Hi,
I am trying to check the levels of HMGCoA Reductase gene expression in rats that i've dosed with a drug designed to decrease cholesterol levels.
I used TriZOL to extract mRNA from hepatocytes, then did an RT-PCR & got cDNA. I chkd the presence of cDNA by amplifying the G6PD gene in the sample. But now i am unable to amplify th HMG gene. The primers r correct. I tried various conc of MgCl2 and used a temp gradient, but it dindt work.
Can ny1 plz tel me what the problem is?
Thanks. All help is appreciated.
redmerlin