Setting Showering to HERWIG7 in MG 2.9.2

I am trying to set showering in MADGRAPH (2.9.2) to HERWIG7

My proc card looks like this:

##########################################
import model RPVMSSM_UFO

define susysq = ul ur dl dr cl cr sl sr t1 t2 b1 b2
define susysq~ = ul~ ur~ dl~ dr~ cl~ cr~ sl~ sr~ t1~ t2~ b1~ b2~
shower = HERWIGPP
generate p p > go go QED=0 RPV=0 / susysq susysq~ @1
add process p p > go go j QED=0 RPV=0 / susysq susysq~ @2
add process p p > go go j j QED=0 RPV=0 / susysq susysq~ @3

# Output processes to MadEvent directory
output -f -nojpeg
##############################################

While running this on CERN lxplus machine, I get a prompt that says:

generate 23:14:10 shower = HERWIGPP
generate 23:14:10 Command "shower" not recognized, please try again

I tried parton_shower but it doesn't work either.

How would one set the showering to HERWIG7?