onUpdate, Player rotation angle setting & minecraft side help

I've created a some sort of weapon item, which does a screen uplift when shooting

I use this in EntityPlayer onItemUsing:

entityPlayer.rotationPitch -= this.upliftRadius;

and it works quite well.

But when I try to do the rotation recover inside onUpdate(..)method,something onusual happened.

inside my abstract class WeaponGeneral:

public InformationWeapon onWpnUpdate(ItemStack par1ItemStack, World par2World, Entity par3Entity, int par4, boolean par5){

	if(!(par3Entity instanceof EntityPlayer))
		return null;

	InformationWeapon information = loadInformation(par1ItemStack, (EntityPlayer) par3Entity);

	ItemStack currentItem = ((EntityPlayer)par3Entity).inventory.getCurrentItem();
	if(currentItem == null || !currentItem.equals(par1ItemStack))
		return null;	

	if(information == null){
		System.err.println(par2World.isRemote + " side is null");
		return null;
	}
	if(!par2World.isRemote)
		return information;
	if(information.isRecovering){
		par3Entity.rotationPitch += recoverRadius;
		information.recoverTick++;
		if(information.recoverTick >= (upLiftRadius / recoverRadius))
			information.isRecovering = false;
	}		
	return information;

}

well,InformationWeapon is a class I've written to provide information for ItemStack,you can skip this.

When I extend this WeaponGeneral class, and call onWeaponUpdate(...) in onUpdate(...) method, it doesn't work quite well.

1:On INTERGRATED Server, both Creative mode and Survival mode works quite well.

2:On CLIENT/SERVER testing, Creative mode works quite well;

BUT when testing in survival mode, player's rotationpitch SOMETIMES recover, MOST TIMES stay the same.

I tried debugging in console,

the result showing when in Survival Mode, each recovering process adds the player's rotationPitch.

but in the next recovering process, the rotationPitch went back to the oringinal pitch, as if the screen output is lying.

So what am I supposed to do to fix this?

Thanks a lot >)