its been discussed earlier check this https://scn.sap.com/thread/1993217
Leave request is based on TMW http://scn.sap.com/thread/1924723
Now then since it was a missing functionality and provided with this note
WDABAP: Deducted quota not shown while sending Leave Request 1932288 So implement these notes to get what you need 
PS: 1819411 - Time accounts application shows incorrect data
1806182 ESS LEA: No (error) messages in ESS Leave Request