[Zope] Error Value: len() of unsized object at SQL method

[Kerekes Lajos]

Hello!

I have an SQL select. If it gives no result, I get this error message
Error Type: TypeError
Error Value: len() of unsized object

How can I manage it?
 I tried this:
<dtml-in ZSQLSelect>
foo, bar.....
<dtml-else>
no result
</dtml-in>

but still get the error.

   Thanks:

    Lajos Kerekes