Error spam in console. Everything works

[j2ghz]

Title: Error spam in console. Everything works

Version: 0.5.1

OS: Windows 8 Pro 64-bit Upgraded

Java Version: Version 7 Update 10

Description of Problem:

This error writes in concole 2-3 times / second. As far as I can tell, everything works normally.

Error Messages:

Error Log:

2013-01-07 17:54:48 [WARNING] [iC2] API ERROR: ic2.core.block.machine.tileentity.TileEntityElecFurnace@634680c4 didn't implement demandsEnergy() properly, no energy from injectEnergy accepted although demandsEnergy() returned true.