diff --git a/agents/agentreq.go b/agents/agentreq.go
index 543fa0dfb..f160dce7f 100644
--- a/agents/agentreq.go
+++ b/agents/agentreq.go
@@ -98,10 +98,12 @@ func (ar *AgentRequest) FieldAsInterface(fldPath []string) (val interface{}, err
 // FieldAsString implements engine.DataProvider
 func (ar *AgentRequest) FieldAsString(fldPath []string) (val string, err error) {
 	var iface interface{}
-
 	if iface, err = ar.FieldAsInterface(fldPath); err != nil {
 		return
 	}
+	if nmItems, isNMItems := iface.([]*config.NMItem); isNMItems { // special handling of NMItems, take the last value out of it
+		iface = nmItems[len(nmItems)-1].Data // could be we need nil protection here
+	}
 	return utils.IfaceAsString(iface)
 }
 
@@ -130,7 +132,7 @@ func (ar *AgentRequest) AsNavigableMap(tplFlds []*config.FCTemplate) (
 		} else {
 			valSet = nMFields.([]*config.NMItem) // start from previous stored fields
 			if tplFld.Type == utils.META_COMPOSED {
-				prevNMItem := valSet[len(valSet)-1]
+				prevNMItem := valSet[len(valSet)-1] // could be we need nil protection here
 				prevDataStr, err := utils.IfaceAsString(prevNMItem.Data)
 				if err != nil {
 					return nil, err
diff --git a/agents/diam_it_test.go b/agents/diam_it_test.go
index ed7966011..c1ac278e7 100644
--- a/agents/diam_it_test.go
+++ b/agents/diam_it_test.go
@@ -288,6 +288,16 @@ func testDiamItDryRun(t *testing.T) {
 				t.Errorf("expecting: 100, received: <%s>", val)
 			}
 		}
+		eVal = "6" // sum of items
+		if avps, err := msg.FindAVPsWithPath([]interface{}{"Granted-Service-Unit", "CC-Time"}, dict.UndefinedVendorID); err != nil {
+			t.Error(err)
+		} else if len(avps) == 0 {
+			t.Error("Missing AVP")
+		} else if val, err := diamAVPAsString(avps[0]); err != nil {
+			t.Error(err)
+		} else if val != eVal {
+			t.Errorf("expecting: %s, received: <%s>", eVal, val)
+		}
 	}
 }
 
diff --git a/data/conf/samples/diamagent/dryrun.json b/data/conf/samples/diamagent/dryrun.json
index 7b0aac433..72eda2cec 100644
--- a/data/conf/samples/diamagent/dryrun.json
+++ b/data/conf/samples/diamagent/dryrun.json
@@ -24,7 +24,7 @@
 					"type": "*constant", "value": "65000","new_branch": true},
          		{"tag": "RatingGroup",  "field_id": "Multiple-Services-Credit-Control.Rating-Group",
          			"type": "*constant", "value": "100","new_branch": true},
-         		{"tag": "LastUsed", "field_id": "LastUsed", "type": "*sum", 
+         		{"tag": "GrantedUsage", "field_id": "Granted-Service-Unit.CC-Time", "type": "*sum", 
          			"value": "~*cgreq.Val1;~*cgreq.Val2;~*cgreq.Val3"}, 
 			],
 		},