Mighty Script - Print Random Number with In Game Message shows always "null"

Create a new number (integer).

Create a script that generates a random number on the previous created integer. 

Print the integer now to the player's screen (e.g. with a "Show Ingame Message" and as content you select the integer).

Export and Quicktest the map.

Ingame Message shows always "null" - no matter how often you fire the script and generate numbers.