diff --git a/src/kiri-mode/cam/client.js b/src/kiri-mode/cam/client.js
index 770e480a..d4e9c033 100644
--- a/src/kiri-mode/cam/client.js
+++ b/src/kiri-mode/cam/client.js
@@ -1047,7 +1047,7 @@ CAM.init = function(kiri, api) {
             let { selected } = object;
             let { widget, poly } = object.trace;
             for (let add of widget.adds) {
-                if (add.selected !== selected && add.trace.poly.getZ() === poly.getZ()) {
+                if (add.trace && add.selected !== selected && add.trace.poly.getZ() === poly.getZ()) {
                     func.traceToggle(add);
                 }
             }
@@ -1055,6 +1055,7 @@ CAM.init = function(kiri, api) {
     };
     func.traceToggle = function(obj, skip) {
         let material = obj.material[0];
+        if (!material) return;
         let { color, colorSave } = material;
         let { widget, poly } = obj.trace;
         let areas = poppedRec.areas;
diff --git a/src/kiri-mode/cam/slice.js b/src/kiri-mode/cam/slice.js
index c86b77da..457d43ac 100644
--- a/src/kiri-mode/cam/slice.js
+++ b/src/kiri-mode/cam/slice.js
@@ -334,7 +334,8 @@ CAM.traces = async function(settings, widget, single) {
         return false;
     }
     let slicer = new kiri.cam_slicer(widget);
-    let indices = [...new Set(Object.keys(slicer.zFlat)
+    let zees = Object.assign({}, slicer.zFlat, slicer.zLine);
+    let indices = [...new Set(Object.keys(zees)
             .map(kv => parseFloat(kv).round(5))
             .appendAll(Object.entries(single ? slicer.zLine : {}).map(ze => {
                 let [ zk, zv ] = ze;