Hi Rahul, Kiran,
I checked the Data modelling - Generate data model specific structures which is perfect and the Basic Type is also GLMAST01, Imported the Note as given.. But nothing worked.
The problem is in MDG itself the segment E1SKB1M is not getting generated. When I see the IDOC status in WE02 for Outbound IDOCs Please see the screenshot attached. 
Am I going somewhere in the process?
Kind Regards,
Thamizharasi N