It looks like the function you are using is the function known in English as
String(), not Str().
The empty (Null) fields are the problem, as a Null value is not a legal
argument for the String() function.
If the query was to be executed within Access, you could use the NZ (Null to
Zero) function, but as it is to be used in a Web application, you'll need
the IIf (Immediate If) function. Here's an example ...
SELECT IIf([Num1] Is Null,"",String$([Num1],"X")) AS Expr1
Brendan Reynolds (MVP)
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