error in image field when using CASE statement

I've this Stored procedure on a SQLserver 2000 SP3:

SELECT *,CASE immagine WHEN NULL THEN 0 ELSE 1 END AS hasImage
FROM Squadre WHERE squadra = @.squadra

this is a flag that returns if the image field is present or not..
i've a lot of this type of stored procedures.. but this one returns me an error..

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Microsoft SQL-DMO (ODBC SQLState: 42000)
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Errore 306: The text, ntext, and image data types cannot be compared or sorted, except when using IS NULL or LIKE operator.
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OK
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An i can't save.. why?
reme,ber that in the same Db there's other Stored like this.. the same syntax and the same field or table.. can anyone help me??So, are you saying that "sometimes" it works and sometimes it doesn't?

This should work "always":

SELECT *,CASE WHEN immagine IS NULL THEN 0 ELSE 1 END AS hasImage
FROM Squadre WHERE squadra = @.squadra

But exclude the image field from the SELECT list, unless you really intend to use it.|||i must use it!!!