1.5.0: mobs won't spawn

[alienzzzzz01]

Version:
1.5.0

What is the bug:
Hey I can't get vanilla mobs to spawn in a mob farm. The difficulty is on hard, there's three block vertical clearance and i've tried increasing the size i've tried sizes from five by five to 25 by 25. I just want a lot of bonemeal without going to the nether. I've tried putting the farm in the air, in the ground, and nothing.

Mod & Version:


Paste.feed-the-beast.com log:


Can it be repeated:


Known Fix:

 

[Trisscar]

You could always try a skeleton spawner. There's the vanilla one that can be moved by various means, the MFR one, the Ender IO one, one or two Thaumcraft ones.....