Required custom field on solved bug work only with checkbox

[|UVI|]

Hi,

I've a serious trouble using Mantis v 1.1.1 on production environment.
I have to add a new custom field required only on "solved" status, initially not setted during bug report.

Using Radio or enumeration, when I solve the bug, I see the "*" on that field, but If I submit the bug without select a value, the system works as if the field is not required.

Using Checkbox, the field works correctly and raise an error "The field XXXXX is empty".

There is a way to assume same behaviour also on enumeration or radio type of field??????

Please help me