Hi Muthu,
I assume you have your form for the invoice in .net form.
You can connect to DI API using :
Dim oComp as New SAPbobsCOM.Company
oComp.DBServerType = MSSql 2008 (Or your type of server)
oComp.Server = "AddressOfYourServer" (include the instance if you are using it)
oComp.LicenseServer = "AddressOfYourLicenseServer:30000" (30000 is the port)
oComp.CompanyDB = "SAPcompany to connect to"
oComp.UserName = "SAPUserName"
oComp.PassWord = "SAPPassword"
oComp.Connect()
IF not oComp.Connected THEN
msgbox(oComp.GetLastErrorDescription)
END IF
On how to create an invoice, you should check out the samples under your SDK folder.
Regards
Edy