Help: Why IN-Operator With Select-Statement It Doesn't Work? But With Given Values It Works

Hello to all,

i have a problem with IN-Operator. I cann't resolve it. I hope that somebody can help me.

I have a IN_Operator sql query like this, this sql query can work. it means that i can get a result 3418:

declare @IDM int;

declare @IDO varchar(8000);

set @IDM = 3418;

set @IDO = '3430' 

select *

from wtcomValidRelationships as A

where (A.IDMember = @IDM) and ( @IDO in (3428 , 3430 , 3436 , 3452 , 3460 , 3472 , 3437 , 3422 , 3468 , 3470 , 3451 , 3623 , 3475 , 3595 , 3709 , 3723 , 3594 , 3864 , 3453 , 4080 ))

but these numbers (3428 , 3430 , 3436 , 3452 , 3460 , 3472 , 3437 , 3422 , 3468 , 3470 , 3451 , 3623 , 3475 , 3595 , 3709 , 3723 , 3594 , 3864 , 3453 , 4080 ) come from a select-statement. so if i use select-statement in this query, i get nothing back. this query like this one:select *

from wtcomValidRelationships as A

where (A.IDMember = @IDM) and ( @IDO in (select B.RelationshipIDs from wtcomValidRelationships as B where B.IDMember = @IDM))

I have checked that man can use IN-Operator with select-statement. I don't know why it doesn't work with me. Could somebody help me? Thanks

I use MS SQL 2005 Server Management Stadio Express

Thanks a million and Best regards

Sha