Fabio,

From the VFP help
QUOTE
Evaluates a character expression and returns the result.
EVALUATE(cExpression)
UNQUOTE

As NULL is not an expression, you cannot evaluate it, thus you get an error as desirable, expactable and preventable.
You may want to try EVALUATE("NULL") which is a character expression with the NULL value. This returns NULL.

HTH



>Hi Martin,
>
>>Of course. Evaluate takes a string parameter.
>
>But x is a null string.
>
>Fabio