Disaggregation based on another Key figure

I have a query. We have keyfigures "Stat Forecast T/D" & "Revised Budget" both are disaggregating based on
another key figure 'Customer planner forecast'.

The value in the 'Customer planner forecast' is '0' in Planning book for week 26.2016.

But the value for 'Stat Forecast T/D and "Revised Budget" showing
incorrect value. The KF values for Stat and Revised Budg are maintained at brand/channel level while Customer planner forecast at SKU/Customer level.

Can anyone tell me how disaggregation takes place when the
value is zero in disaggregation key figure ie in our case 'Customer planner forecast' and the bigger problem is why it can be for only one particular week (i.e 26.2016).

I have also checked data backups and there is no value in "Customer Planner forecast" meaning that nobody has manually changed it recently.

Urgent reply is appreciated 😊

Thanks
and Regards,

Shaikh