Proc SQL Select Distinct SAS

I have a dataset, Have, that looks like this:-

ID    Group  Label_T
1763    A     Y
1763    A     M
6372    B     M

I want to join this dataset onto another dataset by distinct ID and have a conditional based on the variable Group like this:-

proc sql;
create table want as 
  select a.ID
  a.Qty
  (case when b.Group = 'A' then 'Right'
        when b.Group = 'B' then 'Left' end) as Category
 from work.test a
   left join (select distinct ID from work.have) b
        on a.ID=b.ID
;
quit;

I want the dataset to look like this:-

ID      Qty   Category
1763     28     Right
6372     30     Left
3908     41     <blank>

And for the IDs that weren't in the Have dataset to be left blank for the column Category. When I run this I keep getting the error: "Column Group could not be found in the table/view identified with the correlation name b." The column Group is not in the work.test dataset. I think I might have to have the conditional with ID instead of Group but I do I need an additional data set for the conditional then join?

If you have not Group column in work.test then you should use that column in subquery. It will work fine

proc sql;
create table want as 
  select a.ID
  a.Qty
  (case when b.Group = 'A' then 'Right'
        when b.Group = 'B' then 'Left' end) as Category
 from work.test a
   left join (select distinct ID, Group from work.have) b
        on a.ID=b.ID
;
quit;