If Statement Help - For Jun (Urgent)

Jun,

Thank you for your help but when I put the NOT IN like you suggested I am still getting the error of:

Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

Here is the code again:

--If a request is not equal to the request from Jason's table then populate the table.
if (select REQUEST from TEAM3B_PULL_TOTAL_TST) Not In (select REQUEST from REQUEST_BUS_REQ_TST)
begin
Insert into REQUEST_BUS_REQ_TST (b.request,b.business_req_id,b.bus_test,b.test_cas e_id,b.test_case_source,b.test_case_descr)
select a.request,a.business_req_id,a.bus_test,a.test_case _id,a.test_case_source,a.test_case as test_case_description
from TEAM3B_PULL_TOTAL_TST as A JOIN REQUEST_BUS_REQ_TST AS B ON A.REQUEST = B.REQUEST
Order by b.REQUEST,b.BUSINESS_REQ_ID,b.TEST_CASE_ID
end