diff --git a/app/Http/Controllers/ActivityController.php b/app/Http/Controllers/ActivityController.php
index f5cf99d..f3c172d 100644
--- a/app/Http/Controllers/ActivityController.php
+++ b/app/Http/Controllers/ActivityController.php
@@ -14,6 +14,7 @@ use App\Models\User;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\DB;
 use Illuminate\Support\Facades\Log;
+use DateTime;
 
 class ActivityController extends Controller
 {
@@ -250,18 +251,29 @@ class ActivityController extends Controller
 		$updateBobot = true;
 		if(!$data = Activity::find($id))
 			return response()->json(['status'=>'failed', 'action'=>'error','message'=>'Data not found!','code'=> 404], 404);
+		$link = Link::where('t_activity_id', $data->id)->get();
+		if ($link) {
+			foreach ($link as $linkData) {
+				$predecessor = Activity::find($linkData->s_activity_id);
+				$start = new DateTime($data->start_date);
+				$end = new DateTime($predecessor->end_date);
+        		$lag = $start->diff($end)->format('%a');
+				$linkData->lag = $lag;
+				$linkData->save();
+			}
+		}
 		$dataUpdate = $request->all();
 
 		$dataUpdate['name'] = $request->text;
 		$dataUpdate['persentase_progress'] = $request->progress*100;
 		$dataUpdate['updated_by'] = $this->currentName;
-    unset($dataUpdate['sortorder']);
+    	unset($dataUpdate['sortorder']);
 		if($data->type_activity!='header')
 			$dataUpdate['type_activity'] = $request->type;
     
-    if($request->has("target")){
-      $this->updateOrder($id, $request->target);    
-    }
+		if($request->has("target")){
+		$this->updateOrder($id, $request->target);    
+		}
 
 		if(!$data->update($dataUpdate))
 			return response()->json(['status'=>'failed', 'action'=>'error','message'=>'data activity failed updated!','code'=>400], 400);