How to check SAPDB return value in Access

Hello, 

I'm facing the followin problem:
To find out if I have to insert new records or if I have to use the old one,
I'm executing a "SELECT lfd_Rueckfragenummer FROM tbl_StaffelRueckm WHERE
Lfd_Rueckfragenummer = <integer>". 
If I execute this in SQL Studio I get the message:
"Statement successfully executed. No result." 
That's ok.

But in Access I'm using this query for defining a recordset. (Set rs =
ODBCConnection.OpenRecordSet("SELECT lfd_Rueckfragenummer FROM
tbl_StaffelRueckm WHERE Lfd_Rueckfragenummer = <integer>)

Now I want to check if I get any information back. If I test
'IsNull(rs(0))', I get false => so it's not null
If I test 'IsEmpty(rs(0)), I get false => so it's not empty.
If I test if rs = "", I get "No current Record".

So how can I check in Access if I get an empty recordsource back from my
query.

Thanks in advance for any hint.
Peter

P.S. If I remember right, in a complete Access environment I could check
this with a "IsNull".