Imputation of categorical variables towards the MODE

[lgutm18]

Hello,

I am trying to perform imputation of missing values with the MODE in a few categorical variables, but have not been successful yet. I'd greatly appreciate some insight. 

[Ksharp]

data have;
 set sashelp.heart(keep=smoking_Status);
run;



proc freq data=have order=freq;
table smoking_Status /out=mode;
run;
data mode2(rename=(smoking_Status=_smoking_Status));
 set mode(keep=smoking_Status where=(smoking_Status is not missing) obs=1);
run;
data want;
 set have;
 if _n_=1 then set mode2;
 if missing(smoking_Status) then smoking_Status=_smoking_Status;
 drop _smoking_Status;
run;