getting strange data in Luciferase-renilla assay - (Mar/21/2013 )

hi guys
I am doing the promega dual luciferase-renilla assay(miRNA testing on UTR)
but my ctrl which for sure was used in other experiments do not go down. Anyway I do not have any desired data about all other samples
renilla reads are really different between different samples but in same cells and I thought it should not differ much between different samples
i got a ratio of Luc per Ren of 1 for my empty vector ctrl but all other samples were higher than 1!
I seeded 70000 cells per well(24well) the next day transfected them and after 24hrs I read the plate
Is there any point that I have missed?any idea?
Thanx

I am not sure what your specific question is. Of course you may have different L/R ratios in different treatments because treatments may altered luc activity. How about the reading of renilla activity alone? Is it pretty consistent across treatments?

renilla between replicates show consistency but among different treatments not
u know the upregulation was not the expected result as a similar experiment already has done by sb else in our lab.even my positive ctrl that I am sure about its downregulation does not work