Form validation

My form validation doesn’t work.
It used to work.

function controle(form) {
var bln=false;
var TotStr = “Volgende items zijn verplicht:nrn”;

if ( form._1_naam.value.length == 0 )
{
TotStr = TotStr + “achternaamnr”;
bln = true;
}

if ( form._2_voornaam.value.length == 0)
{
TotStr = TotStr + “voornaamnr”;
bln = true;
}

if ( form._5_straat.value.length == 0)
{
TotStr = TotStr + “straatnr”;
bln = true;

}

if ( form._9_postcode.value.length == 0)
{
TotStr = TotStr + “postcodenr”;
bln = true;

}

if ( form._8_stad.value.length == 0)
{
TotStr = TotStr + “gemeentenr”;
bln = true;

}

if ( form._11_land.value.length == 0)
{
TotStr = TotStr + “landnr”;
bln = true;

}

if ( form._12_tel.value.length == 0)
{
TotStr = TotStr + “telefoonnummernr”;
bln = true;
}
if ( form._15_info[0].checked ){
if ((form._16_type[0].checked)||(form._16_type[1].checked)||(form._16_type[2].checked)||(form._16_type[3].checked)||(form._16_type[4].checked)||(form._16_type[5].checked)||(form._16_type[6].checked)){
}else{
TotStr = TotStr + “Type professionalnr”;
bln = true;
}
}

if ( form._100_email.value.length == 0)
{
TotStr = TotStr + “email adresnr”;
bln = true;
}

if (bln) {
alert ( TotStr );
return false;
} else {
return true;
}

}

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