Scaling the number of entries in an unbinned histogram

Hi I am trying to scale the number of events by a constant amount for a RooDataSet and am encountering some issues. The section of code that does this is:[code]
RooRealVar Bs_mumumumu(“miT_Bs_min_chiSquared_mass”,“Mass(MeV)”,4222,6522) ;

RooFormulaVar wFunc("w","event weight","10*Bs_mumumumu",Bs_mumumumu);
RooDataSet dh4("dh4","dh4",RooArgSet(Bs_mumumumu),WeightVar("wFunc"),Import(*tree4));

The error that I get is
WARNING:DataHandling – RooDataSet::RooDataSet(dh4) WARNING: designated weight variable wFunc not found in set of variables, no weighting will be assigned

It seems that I get no scaling for any function I use. Any help would be greatly appreciated.