Overlay an External DS

I'm trying to overlay an external DS that gets populated by an SQL
statement.  When I do NOT include the data, the DS is populated
correctly: if I add the overlay, the DS is blank even though the SQL
statement has no trouble finding the record.

<psuedo-code>

// this way extDS gets populated
d extDS        e ds                            extname(EXTDS)
...
c/exec SQL
c+   Fetch next 
c+    from myCursor 
c+    into :extDS
c/end-exec

// this way extDS (and hence extDSovr) does NOT get populated
// elem is the correct number of fields in EXTDS
// All fields in EXTDS are defined the same: 100a
d extDS        e ds                            extname(EXTDS)
d extDSovr                             100a    overlay(extDS) %dim(elem)
...
c/exec SQL
c+   Fetch next 
c+    from myCursor 
c+    into :extDS
c/end-exec

</psuedo-code>

Any idea why this is happening or even better how to fix it?

Thanks!

Joel
http://www.rpgnext.com