Naveen,
Your ACCTYPE is AST/LEQ- Thease types of accounts are Balance sheet accounts and are YTD in nature by default. This means that tha values in these accounts are till that period. So If I have values as below.
Jan Feb March Q1
100 150 300 300
The value of 150 in feb is that including 100 of Jan as its the value till Feb. The periodic value for Feb would be 50. The value of march 300 is that including both 100 of jan 50 of Feb and 150 of March. So the value 300 is the value till March and hence the same value will goto Q1. This is how Balance sheet accounts (AST and LEQ) are supposed to behave. You are seeing Q1 as 0 coz you March value is 0 which means the value till March has become 0.
EXP and INC accounts are periodic in nature. So if you post data as below.
Jan Feb March Q1
100 200 300 600
The values 100 200 and 300 are only for that period and does not include the previous month balances.
YTD measure for above posting will show you
Jan Feb March Q1
100 300 600 600
I hope this clears your doubt. If still in doubt Please read more on ACC Types and storage types at SAP Help.
Regards
Nikhil