SAP Message TU010 - Enter a permissible period length

Diagnosis
You have made an incorrect entry in the field for period length. Theperiod may never be longer than 12 months. The following values arepermitted:
Period length Period category
1 Year
1 Month
2 Months
3 Months
4 Months
6 Months
12 Months

Procedure
Please make a valid entry.