Accesing user defined function in Access 2000

[altctldel]

I had two fields(Field1 , Field2) in query. I want to replace a specific character occurance (Let the character be @) in FIELD2 by value of FIELD1.

there is no Built-in REPLACE function in ACCESS 2000.

So i tried writing a module for
replacing( Module Name Rep()) and
successfully able to execute the query in Access 2000.

When I tried to execute same query from Visual Basic, It displayed an
ODBC ERROR: Undefined Function Rep().