I'm confused. You've posted this on the eConnect forum, and you say that you're using eConnect 10, but you also say that you 'made some customizations on SOP screen'.
In what enviromnent are the customizations made? VSTools? VBA? DEX?
Assuming that the issue really is in the eConnect code, think about how your app is connecting to SQL. Your code sends to the eConnect dll, and the eConnect dll sends to SQL. What permissions are you using there?
Go back to the help document and read the section on configuring DCOM. Carefully.
I'll bet that what you're trying to do is not possible. It seems to me that DCOM is going to require a network account, and from a workstation environment you're not going to have that.
Search this forum for references to 'web service', in the past I've used a web service to solve this problem by packaging eConnect as an XML document and sending it to a web service on the SQL server. There are no DCOM issues then.