javascript not working for time calculation

I AM MAKING A TRIP SHEET FORM AND I HAVE THE CODE TO CALCUALTE TIME BUT IT IS SIMPLY NOT WORKING. I NEED HELP PLEASE! I WILL POST THE SCRIPT BELOW

function HHMM2Num(cFormat, cTime) {

var cDate = "1-Jan-1970 " + cTime;

var oDate = util.scand("dd-mmm-yyyy " + cFormat, cDate);

var nDate = oDate.getTime();
( 1000 milliseconds in second, 60 seconds in minute)
return Math.floor(nDate / (1000 * 60));
}

function Num2hMM(nMin) {

var nHrs = Math.floor(nMin / 60);

var nMins = nMin % 60;

return util.printf("%,201.0f:%,202.0f", Math.floor(nMin / 60), nMin % 60);
}

var cMeetingsIn = this.getField("MEETINGSIN").value;
var cMeetingsOut = this.getField("MEETINGSOUT").value;
var cLoadIn = this.getField("LOADIN").value;
var cLoadOut = this.getField("LOADOUT").value;
var cTravelToIn = this.getField("TRAVELTOIN").value;
var cTravelToOut = this.getField("TRAVELTOOUT").value;
var cSiteIn = this.getField("SITEIN").value;
var cSiteOut = this.getField("SITEOUT").value;
var cTravelFromIn = this.getField("TRAVELFROMIN").value;
var cTravelFromOut = this.getField("TRAVELFROMOUT").value;
var cUnloadOut = this.getField("UNLOADOUT").value;
var cOfficeIn = this.getField("OFFICEIN").value;
var cOfficeOut = this.getField("OFFICEOUT").value;
var cOfficeInOne = this.getField("OFFICEINONE").value;
var cOfficeOutOne = this.getField("OFFICEOUTONE").value;
var cOfficeInTwo = this.getField("OFFICEINTWO").value;
var cOfficeOutTwo = this.getField("OFFICEOUTTWO").value;
var cOfficeInThree = this.getField("OFFICEINTHREE").value;
var cOfficeOutThree = this.getField("OFFICEOUTTHREE").value;

event.value = "";

if(cMeetingsIn != "" && cMeetingsOut != "" && cLoadIn !="" && cLoadOut !="" && cTravelToIn !="" && cTravelToOut !="" && cSiteIn !="" &&  cSiteOut !="" && cTravelFromIn !="" && cTravelFromOut !="" && cUnloadOut !="" && cOfficeIn !="" && cOfficeOut !="" && cOfficeInOne !="" && cOfficeOutOne !="" && cOfficeInTwo !="" && cOfficeOutTwo !="" && cOfficeInThree !="" && cOfficeOutThree !="") {
// convert time strings to minutes using HHMM2Num function
var nMeetingsIn = HHMM2Num("h:MM tt", cMeetingsIn);
var nMeetingsOut = HHMM2Num("h:MM tt", cMeetingsOut);
var nLoadIn = HHMM2Num("h:MM tt", cLoadIn);
var nLoadOut = HHMM2Num("h:MM tt", cLoadOut);
var nTravelToIn = HHMM2Num("h:MM tt", cTravelToIn);
var nTravelToOut = HHMM2Num("h:MM tt", cTravelToOut);
var nSiteIn = HHMM2Num("h:MM tt", cSiteIn);
var nSiteOut = HHMM2Num("h:MM tt", cSiteOut);
var nTravelFromIn = HHMM2Num("h:MM tt", cTravelFromIn);
var nTravelFromOut = HHMM2Num("h:MM tt", cTravelFromOut);
var nUnloadOut = HHMM2Num("h:MM tt", cUnloadOut);
var nOfficeIn = HHMM2Num("h:MM tt", cOfficeIn);
var nOfficeOut = HHMM2Num("h:MM tt", cOfficeOut);
var nOfficeInOne = HHMM2Num("h:MM tt", cOfficeInOne);
var nOfficeOutOne = HHMM2Num("h:MM tt", cOfficeOutOne);
var nOfficeInTwo = HHMM2Num("h:MM tt", cOfficeInTwo);
var nOfficeOutTwo = HHMM2Num("h:MM tt", cOfficeOutTwo);
var nOfficeInThree = HHMM2Num("h:MM tt", cOfficeInThree);
var nOfficeOutThree = HHMM2Num("h:MM tt", cOfficeOutThree);
var nDiff = nMeetingsIn - nMeetingOut + nLoadIn - nLoadOut + nTravelToIn - nTravelToOut + nSiteIn - nSiteOut + nTravelFromIn - nTravelFromOut + nTravelFromOut - nUnloadOut + nOfficeIn - nOfficeOut + nOfficeInOne - nOfficeOutOne + nOfficeInTwo - nOfficeOutTwo + nOfficeInThree - nOfficeOutThree;

nDiff -= this.getField("LUNCH").value;

event.value = Num2hMM(nDiff);