Axbound field Date selection in EP

1.I am creating New Absence request in EP

path : Time and attendance >>Absence requests >> New Absence request

2. Above screen shows Start Date, End Date, Hours.. Etc..

I need to calculate hours on change of Start Date, End Date. initially Start Date, End Date are edit method field . i tried but i am not getting hours

after this i tried with  Itemtemplate fields , after entering the Data in Description field i lost date in star date and end date

I tried with datepicker  , I am unable to get the hours at  first time date selection ,able to get hour selecting two times  of end date or star date

I tried with bound fields Start Date, End Date

<dynamics:AxBoundFieldDataField="StartDate"DataSet="HcmEPAbsenceRequestEdit"DataSetView="HRMAbsenceRequest"   AutoPostBack="true"OnDataChanged="type_OnDataChanged">

                   </dynamics:AxBoundField>

                   <dynamics:AxBoundFieldDataField="EndDate"DataSet="HcmEPAbsenceRequestEdit"DataSetView="HRMAbsenceRequest"  AutoPostBack="true"  OnDataChanged="type_OnDataChanged">

                   </dynamics:AxBoundField>  

OnDataChanged is not firing after selecting end date or start date

 I need on selection of date 

Can any one help me on this