subset problem

Dear All,

I'm trying to run a model on a subset of my data 
identified by year = 2002. Does anyone know whats wrong 
with the syntax below:

glmmPQL(desm~desdat,random=~1|male,family=quasibinomial,
data=mcare,subset=year=2002)

I get an error message all the time, but it worked with 
string variables (like: subset=sex=="M").

Thanks,
Istvan