Can not access the member items of an assembly record

I am at wits end and it's probably something stupid.

I'm looping through items from a specific transaction and then checking the type. When I come across a kit, assembly, or group, I want to load that specific item and then look further into its members to look for certain field attributes. Everytime I do this, I get a line count of 0. Am I forgetting a step or missing something?

 // recType and recId are correct, the record loads fine  var rec = nlapiLoadRecord(recType,recId);  if ( !rec ) { return; }  alert('load record good');    var memberCnt = rec.getLineItemCount('memberitem');  alert('member count: '+memberCnt);