MD70 not working with split

Hi,
    I am using MD70 to copy the material master forecast into demand
management. I have defined the period split as 0 weeks to be split in
days and 3 months to be split in weeks. However the MD70 split does not
work. I am expecting the split to cause the next 3 months to be split
in weeks and then the remaining forecast horizon to remain in months.
However I see the split only happens for 5 weeks starting from the
beginning of this month and then from next month the split is monthly.
I cannot figure out where the system is taking its split logic from. I
have made the assignment to OMPH tcode and in OMPA. Can you assist.

Thanks