Earned Leaves Configuration Not working

Dear Sir,

I am working on SAP R/3 Enterprise v 4.7.

I need to configure Leaves in my company, the characteristics of which are as follows:

EARNED LEAVES

1. 20 Working Days=1 EL (Calendar Year)

2. A maximum of 30 ELs may be accumulated

3. Any quota balance over and above 30 ELs should be automatically be encahsed 1st Jan of the consecutive year.

4. Half Day EL is not allowed to any employee

Please help me with the configuration.

Regards,