Hi Furkan 

I had a look at your project set up the short code is set as TANK_BATTLE with no s.

Changing this will fix this issue.

Regards

Katie

Hi Furkan

Have you tried to make the request in the test harness?

Do you get the same error?

If you do can you give me the request you are making in the test harness please.

Cheers

Katie

Hi Furkan

If you are not using the action parameter remove it from the request, this will remove the error you are getting in the test harness

Regards

Katie