Need some help with a javascript validation loop

My apologies - I'm sure the answer it dead simple here but I've got a tight deadline and am having trouble with this validation and need some help.

Part of my form allows a person to add up to 10 volunteers and fill out their information too.  The additional volunteers are added one at a time.  The fields are named ldrFName1, ldrLName1, ldrFName2, ldrLName2, etc up to 10 (there's also address, city, zip, phone and all but I can extrapolate the rest).

I know I can loop through the fields and save a ton of hand coding but, so far, my feeble attempts aren't working for me.  I know I have to be building the dynamic field name wrong and although it is alerting correctly, the validation isn't stopping - so I know the field names are being recognized or I've got an error that I don't see.

I'm getting the count for the loop from a hidden field that is updated as additional volunteer fields are added or subtracted by the buttons that add a new volunteer or cancel one.

If I were just writing out the validation for a single field, it would look something like the attached code:

So if I have to loop it, how do I properly write the field names within the loop so they're picked up by the validation?

BTW, I'm not including any of the supporting functions for the validation but can if needed.

Thanks a lot in advance.

function validateForm(theForm){
	strMessage ='Please correct the following problem(s)!\n\n';
	var iErrorCount = 0;
	var f = document.theForm;


/*= VALIDATE LEADER FIRST NAME =*/
for (var i=0; i<f.ldrCounter.value; ++1) {
	if(notEmpty(f.ldrFName1.value)==false){
		strMessage = strMessage +"The first name of the leader is required.\n";
		if(iErrorCount ==0){
			f.ldrFName1.focus();
			f.ldrFName1.style.background = errorColor;
		}
		iErrorCount ++;
	} else {
		f.ldrFName1.style.background = backColor;
	}
}

	if (iErrorCount > 0){
		alert(strMessage);
		strMessage ='';
		iErrorCount =0;
		return false;
	}else{
	}
}

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