Variable <skill.var.bow-tension> can't be defined in the Onshoot aura

The variable <skill.var.bow-tension> is always UNDEFINE when used in a skill. This is the skill I use to test it: Test: Skills:

• onShoot{auraName=test_shoot;onShoot=[- message{m="<skill.var.bow-tension>"}];d=100;cE=true} @self

Current behavior The message sent to the player always shows UNDEFINE instead of the actual value of <skill.var.bow-tension>.