Variables on text(payload) in Action?

Variables on text(payload) in Action?

Hi,
I made Action (variable) which Publish to MQTT device...

My Emulator data is:

  1. [
        {
        "variable": "EXTI1_Trigger",
        "value": "TRUE"
      },
      {
        "variable": "speed",
        "value": 11
      }
      ]  

Bucket is updated correctly.

Action Trigger is set as: exti1_trigger is anything.

Action payload is: $SPEED$ $VALUE$ and I getting message "$SPEED$ TRUE".

What is wrong with this?

It seems that the speed $SPEED$ variable is not recognized and the value $VALUE$ comes from the exti1_trigger variable....