Document.forms Problem

I have some code on a page that will enable/disable a text box if a
checkbox has been checked/unchecked and it seems to be working fine
unless there is only one checkbox and one text box.

Here is the javascript:

function EnableCustLoyaltyNotes(x,y)
{
if (document.frmCustLoyalty.VoidLineID[x].checked ||
document.frmCustLoyalty.UnVoidLineID[x].checked)
{
document.frmCustLoyalty.Notes[y].disabled = false;
}
else
{
document.frmCustLoyalty.Notes[y].disabled = true;
}}

Pretty simple, here is the code on the page:

onClick="EnableCustLoyaltyNotes(Ɔ',Ɔ');"

Any ideas on why its not working?