[XMLEncryption] Illegal key size

Hi all

I have unlimited JCE install in my machine. Normal XMLEncryption works
fine. But when the following algorithm is used it throws an Exception.

http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p

The exception is 

Caused by: org.apache.xml.security.encryption.XMLEncryptionException:
Illegal key size or default parameters
Original Exception was java.security.InvalidKeyException: Illegal key
size or default parameters
        at
org.apache.xml.security.encryption.XMLCipher.encryptData(Unknown Source)
        at
org.apache.xml.security.encryption.XMLCipher.encryptElementContent(Unknown 
Source)
        at org.apache.xml.security.encryption.XMLCipher.doFinal(Unknown
Source)

So how do I come out of this problem?

Thank you,
Dimuthu