ADD_TIME_TO_DATE function does not take into account change of year

Hi,

I've realised that add_time_to_date doesn't take into account whether we are at the beginning of the year. For example, if I pass the following parameter to the function:

CALL FUNCTION 'ADD_TIME_TO_DATE' "

EXPORTING

i_idate = '20130101'

i_time = '-1'

i_iprkz = '2'

IMPORTING

o_idate = " sy-datum

I get the value 01.00.2013.

Can anybody help me or give another function which works in this case?

Thanks in advance.

Regards.