Check Box value issue, Error in bizflowEntry Action required and object

Hi,
im having a problem in my form when i get a value from the ERA mapping that is value its "true" the page in the internet explorer gives me an error that u can see in the attach, my first option was the validacion script for the check box that hiddes or block a layout group but its give me the same error if i dont put the validation script..... so i change the default value of "true"--->"verdadero" for the checkbox and it works fine for a while ...now gives me the same error again i dont know how i can fix this, i already try to create a JS script and have the same results this is my script its load in the onbeforeload event in the page


if(document.getElementById('chk_medio_dia').checked == false)
{
document.getElementById('group_info_4').style.display = 'none';
}
else
{
document.getElementById('group_info_4').style.display = 'block';
return;
}


this error only occurres when the value of the checkbox its "false" if the value of the checkbox its tickled by "verdadero" the page dont have errors, if you can help me with this issue please i will totally thankful. [hr][/hr]
btw the error begins to trigger out when the domain url for bizflow changes to https, but other proyects run just fine with that change so i discarted that option, and i already patched my webmaker to the 7 patch