I am doing a RankProd for my expression set 

my eset has 7 observation with 6 controls and 1 treatment

my cl is 0 0 0 0 0 0 1

when I run the code

RP.out = RP(exprs(eset), cl, logged=TRUE, rand=123)

I get this error 

Error in vector("list" , nrow(gr2)) : invalid 'length' argument

I am not sure how to change that gr2 to gr1 if that is the issue. 

my RankProd is version 3.4.0 and my R is 3.5.0