Customizable form doesn't show

Hello people!
I have a problem with customizable form. It simply doesn’t show on the page. Do I have to add some additional php code to show it or what can cause the problem ?

Is this using the userforms module, or is it a custom form in a controller?

If the former, does your template (or the content editor) contain the $UserDefinedForm tag?

If the latter, does your template contain the right form tag to match the form function name?