Year Not Converting Properly in Business Objects Data Services XI 3.0

HI,

When I am converting string to date datatype the year value not converting correctly.

When I used this below example

to_date('31-Jan-15','DD-Mon-YY')

it is giving 31-Jan-1915 instead of 31-Jan-2015

that to this problem came when year(yy) value is greater than or equal to 15

if year(yy) value is less than or equal to 14 then its working fine.

I tried with other option with 'RR'

to_date( '31-Jan-15','DD-MON-RRRR')

Cannot convert string <31-JAN-15> to date using format string <DD-MON-RRRR>

please help me to resolve this......

Thank you so much in advance...