The solution is replace the funtion isHoneypotSpam for
function isHoneypotSpam( formID ) {
var honeypotField = document.getElementById( 'frm_email_' + formID );
if ( honeypotField === null ) {
honeypotField = document.getElementById( 'frm_verify_' + formID );
}
return honeypotField !== null && honeypotField.value !== '';
}
at formidablepro.js and formidablepro.min.js