Script on order items trigger not firing!

Not sure why but the following code fires when a PO is generating from the UI but not for the order items page that generates POs: 

       function purchaseorderderform(type)   {      if(type== 'orderitems' || type== 'create'){       try    {       nlapiLogExecution('DEBUG','Starting PO Load', 'Loading...');     var iPurchaseOrder = nlapiGetRecordId();     var objPurchaseOrder = nlapiLoadRecord('purchaseorder',iPurchaseOrder);     nlapiLogExecution('DEBUG','Starting Custom Form: ', objPurchaseOrder.getFieldText ('customform'));     var iVendor = objPurchaseOrder.getFieldValue ('entity');     nlapiLogExecution('DEBUG','Vendor: ', objPurchaseOrder.getFieldText ('entity'));        if (iVendor == '204')     {      objPurchaseOrder.setFieldValue('customform','136');     }     else if(iVendor == '135')     {      objPurchaseOrder.setFieldValue('customform','135');     }     else if(iVendor == '25858')     {      objPurchaseOrder.setFieldValue('customform','103');     }       else if(iVendor == '22019')     {      objPurchaseOrder.setFetFieldValue('customform','103');     }       else if(iVendor == '18157')     {      objPurchaseOrder.setFetFieldValue('customform','103');     }     else     {      objPurchaseOrder.setFetFieldValue('customform','98');     }            nlapiLogExecution('DEBUG','Finishing Custom Form: ',objPurchaseOrder.getFieldText ('customform'));      var iSaved = nlapiSubmitRecord(objPurchaseOrder);     nlapiLogExecution('DEBUG','Submitting PO Load', 'Done: ' + iSaved);        }    catch(err)    {     nlapiLogExecution('DEBUG','Error Message: ', getErrorMsg(err));