Lpc2000

I'm running 4 pwm channels in single edge operation. I am sometimes 
not getting the shadow register latched into the match registers. If 
I use the following code I sometimes get a glitch where the latch 
register doesn't cause the the value to get loaded into the match 
register.

void LPC210xSetPwm1(uint16_t PwmValue)
{
 PWMMR1 = PwmValue;	
 PWMLER = 0x0002;	
}

void LPC210xSetPwm2(uint16_t PwmValue)
{
 PWMMR2 = PwmValue;
 PWMLER = 0x0004;	
}

etc

If I use the following code to latch all 4 pwm shadow registers 
instead of individual I never get a glitch.

void LPC210xSetPwm1(uint16_t PwmValue)
{
 PWMMR1 = PwmValue;	
 PWMLER = 0x002e;	
}

void LPC210xSetPwm2(uint16_t PwmValue)
{
 PWMMR2 = PwmValue;
 PWMLER = 0x002e;	
}

etc

Has anybody had similiar problems or got and explanation. 

regards Doug