For Loop * Sql Task Question About Variables

I want to iterate through a for loop and run some SQL update statements:

I have a variable wk_day that has a scope of the container

I want it to run this code:

update daily_sls_curr set mtd_ty_sls = (
select sum(ty_sls) from daily_sls_curr ci
where ci.fmonth = (select max(fmonth) from daily_sls_curr)
and wk_day <=@wk_day
and ci.store = daily_sls_curr.store
group by store)
where fmonth = (select max(fmonth) from daily_sls_curr)
and wk_day = @wk_day

repeatedly from the loop for 35 days of the fiscal month

When I parse the query, it gripes at the variable

How do I set up the query to work with the variable?

Thanks
JPS