TQUERY & Index file troubles

Hi, tkanks for reading.

I'm using WfW and I have this problem :

I have a TQUERY whit SQL statements like .. SELECT *
FROM XXXXX WHERE XXXX.CODE = 323

If the CODE field is a Index KEY for the table,
the system come up with

 MULTIPLE .NET OPEN FILE ????

No one else is using that !!!!

Can you help me ???

thanks.
Bruno.