ADuC842 DAC glitches,forgot anything?

Hi
I'm trying to do some practice with the 8bit uC AduC 842
When i generate a ramp by means of its DAC there are some glitches,in
different number and position each time a ramp is generated

i vary the DAC out in this way

int i,del;
DACCON=0x0D;  //Async,DAC0 on ,DAC1 off
ADCCON1=0xAC;//Power up ADC/8 + 4 acq clock
..
for(i=0;i<4096;i+=4)
{
 DAC0h=i>> 8;
 DAC0L=i & 0x0FF;

del=10;
while(del){del--}//wait for DAC setting
...


}

reading the value with the ADC itself,that has the same Vref as the
DAC.,shows that the glitches always  happen in cases like this:

misured DAC output at t-1=0x2FC  (next value expected is 0x300,followed by
0x304)
misured DAC output at t   =0x3FF (wrong)
misured DAC output at t +1  =0x304 (correct)


Did i forget anything in initialization that justifies such a behaviour?
How should I modify the code?

Thanks for help,hints  and for your attention

Diego