Can't use score_health in Commandblocks on 1.8Pre-SERVER [Works in Singleplayer]

What I expected to happen was...:
to get an item replaced in my inventory

What actually happened was...:
Nothing - [12:09:35] The entity UUID provided is in an invalid format

Steps to Reproduce:

• • Do everything on the 1.8-Prerelease Vanilla Server **
    1. Get a Commandblock
    2. add a scoreboard called health and objective health
    3. set a commandblock /replaceitem entity @p[score_Health_min=10,score_Health_max=14] slot.armor.legs minecraft:leather_leggings 1 0 {display:}

4. get yourself some damage until you hit ~12 health
5. Open Commandblock, you will see [12:09:35] The entity UUID provided is in an invalid format

That's it. to say it AGAIN: The bug does NOT appear in singleplayer!