QuickForm problem with checkboxes (bug?)

Hi, there is strange problem and I don't know if it's a bug. I've two Quickforms on the same a own instance of quickform each. On the first form there are many fields and one checkbox with the name 'visible'. The second form is just for testing and there are one textfield and one submit button. The defaultsValues for the (first) form are generated from the database. - When I access the page, edit the first form (with the checkbox) everything is fine (i can e.g. switch the checkbox on/off and this value is written correct to the database). I can repeat this as many times as I want and everything is okay. - But when I edit the second form and press "submit" (I get the same page again) the first form is filled with the defaultValues fresh from the database (as expected) but only the checkbox value is wrong because it's not checked (although the database value for the checkbox is unmodified set to checked). I use the type enum('0','1') with default setting '1' in the DB and for the testcase I've set this value really to '1'.. I've printed out the defaultValues before setting and they are exactly the same for the first run and after submitting the second form (my checkbox element IS '1'). I've also printed out the $_REQUEST array and there is no appearance of any key/value of the first form so I supposed that *only* the default values are used to display the first form. I have no duplicate names in both forms. The only thing I find out is that it could have something to do with the function "onQuickFormEvent" in checkbox.php, as I've done a manually $this->setChecked($arg); just before the "return" and I get the checkbox checked (but maybe this is the wrong place). But this could not only be the solution as in this case the checkbox is checked independently from the value in the DB. What I want to mention us, that I don't want to use "Advance Checkbox" as there is JS in it. And I think I've no preoblem with the checkbox element if it's not checked (as I've process this case manually). Could you imagine what's wrong here? Thanks in advance bye Patrick