Custom Record Type - SuiteScript

I have a custom record type that relates to the Opportunity List/Record.  This may sound like a silly question and I typically rely heavily on the suitescript browser (which obviously doesnt exist for customrecordtypes); but how to I reference this sublist on the custom recordtype?  I am trying to get a count of the related Opportunities on pageinit and keep getting "" or -1. There are definitely related records.

function customRecordTypePageInit(type){   var intOppLineItemCount = nlapiGetLineItemCount('custrecord_pm_cr_opportunity');      alert('test'+intOppLineItemCount);  }