added createDevice function but have issues

lib/cloud_service_api.dart

@@ -49,10 +49,21 @@ class CloudServiceAPI{
     Response r = await get(url, headers: headers);
     return json.decode(r.body) as Map<String, dynamic>;
   }
-  Future<bool> createDevice(
-      id,
-      primaryThumbprint,
-      secondaryThumbprint) async{
+  Future<bool> createDevice(id, primaryThumbprint, secondaryThumbprint) async{
+    var url = Uri.https(address, '/api/devices');
+    Response r = await post(
+        url,
+        headers: headers,
+        body: jsonEncode(<String, String>{
+          'id': id,
+          'primaryThumbprint' : primaryThumbprint,
+          'secondaryThumbprint' : secondaryThumbprint
+        })
+    );
+    if (r.statusCode == 200){
+      return true;
+    }
+    debugPrint('Error createDevice: ${r.statusCode.toString()}');
     return false;
   }
 }

lib/cloud_service_ui.dart

@@ -39,6 +39,8 @@ class _CloudService extends State<CloudService>{
             debugPrint('Devices: ${respond1[0].toString()}');
             var respond2 = await cloudServiceAPI.getInformation();
             debugPrint('Information: ${respond2.toString()}');
+            var respond3 = await cloudServiceAPI.createDevice('1', 'asdas', 'sdwe1');
+            debugPrint('CreateDevice: ${respond3.toString()}');
           }, child: const Text("Example"),
         ),
       ),