Error in get(fn) : object 'mice.impute.21.poisson' not found

[dr-jojo]

I keep getting this error: Error in get(fn) : object 'mice.impute.21.poisson' not found
I can get it to work with just regular poisson, but I have a multilevel model. Any help is appreciated

ini=mice(dlong.simp, maxit = 0)
meth=ini$method
pred=ini$predictorMatrix
meth["risk"]= "21.poisson"
pred["risk", ]= c(-2, 1, 1, 1, 1, 1, 1, 2, 0 )

imp=countimp(data=dlong.simp, m=5, method=meth, predictorMatrix=pred, print=FALSE)