Error while triggering the custom mail template

Hi All,

I have created a custom mail template and added that template to the new mail configuration. I also wrote a script, target being Post-Save but I'm encountering error. Below is the screenshot of the error.

Code snippet goes as follows :

Properties params = new Properties();

params.put(new String("TOKEN1"), doc.getDisplayName());

String[] recipients = {"email_ID"};

//recipient=session.getAccount();
sender = session.getAccount();

mailTypeEnum = new MailTypeEnumType(MailTypeEnumType.ODP_CUSTOM_TEMPLATE1);

NotificationUtil.sendNotification(recipients,sender, mailTypeEnum,params,null,null);

Can anyone help me in getting rid of this error.

Reference Blog : http://scn.sap.com/community/sourcing/blog/2012/12/21/sap-sourcing-custom-mail-message-templates