Problems with Reduced Movement Speed Aura {enemies will not slow down}

[Edgecrusher021]

I need an aura that slows movement speed of all nearby enemy units. So I made an ability based on Endurance Aura and put in negative values in the "Movement Speed Increase" field. I've been told this is supposed to work but its not slowing down the units.

The Range is 900 - no problems there
The Allowed Target Types Are: Air, Enemy, Ground, Vulnerable - tested units receive the buff that I gave the ability
The units types that I'm testing the ability on are classified mechanical or organic

Enemy units wont slow down.
Any ideas of how to troubleshoot this problem?

 

[Day-Elven]

This works in my map.

air,ground,organic,enemy,neutral

 

[Edgecrusher021]

Ok, what type of targets (classification) does this aura slow? Obviously not mechanical, but... enemy or neutral organic units that are either ground or air?

EDIT:
Ok, I found my problem.
For those of you who are trying to make a similar skill, make sure that in your 'gameplay constants' menu your unit minimum speed is set to the correct amount. (i.e. If you are testing the ability on a unit that has a speed of 200, but the gameplay minimum speed is 180, its difficult to differentiate between the two speeds so you might think that the skill is not affecting the unit in the right way, but it is)
Be sure to check this. Set your 'Unit - Minimum Speed' constant to 0 or 1 or a low number; this way you can tell if your aura/ability is working.