Forums Scripts & Popups $input with options env

I need $input with editbox and 3 buttons:
//echo -a $input(title,env,prompt,edit)
This returns edit/$null/$null
But with the v option it should return: "$ok, $yes, $no, $cancel for buttons."

If I use //echo -a $input(a,nv) it works correctly. So why doesn't it with e+n+v options?
Is this a bug?