.Call works in R 2 not in R 3

Hi

I inherited a R package done in 2004 that works perfectly in R 2.15.1
and before, but not in R 3.2.2 ( >= 3).

I have already fixed issues with namespace for functions in R 3 but
maybe not all of them.

Here is the error message:
Error in .Call("R_cutree", tree$merge, k, PACKAGE = "stats")
"R_cutree" not available for .Call() for package "stats"

Thanks for your help