Initialize SalesTable.MarkupGroup in OnInitValue event

Hi Friends,

I have a requirement to initialize the value in a field when a record is created. For this i want to default the MarkupGroup in Sales Table to some specific Value when a Sales Order is created.I have created the EventHandler class and copied the form Datasource OnInitValue event and initialized the table buffer as shown below

SalesTable salestable = sender.cursor(); 

salesTable.MarkupGroup ="FRGH";

However the value is not getting initialized when i create a Sales Order. I am trying to understand if the process which i followed is correct and wondering how the Event handler class which i have created will be called/Subscribed when the Sales Order is created.Could you please me in this regard.

Thanks 

Venky