Hi Kalyan
You should not use product type 01A as this is for investments only as the account determination leads to an asset account. To set the company code to allow short positions is also not the way to do it as it will lead the asset account to a credit enty and this is not what you should do.
Please use prodcut type 04X for fixed interested and 04Y for variable interest rates.
This will cover your needs.
Regards
Juerg Heiz