Hey,
I run into the same problem and found that the following Time meas. units must be maintained in the transaction CUNI (see FM SWU_GET_TIME_UNITS)
CONSTANTS $minute TYPE t006-zaehl VALUE 60.
CONSTANTS $hour TYPE t006-zaehl VALUE 3600.
CONSTANTS $day TYPE t006-zaehl VALUE 86400.
CONSTANTS $week TYPE t006-zaehl VALUE 604800.
CONSTANTS $month TYPE t006-zaehl VALUE 2592000.
CONSTANTS $year TYPE t006-zaehl VALUE 31536000.
Regards,
Petr
PS. I my case it was a missing year 
