Hey Atul,
I was passing retrieved customer info to opensession instead of dynamic customer.
Create ddyamic customer record by passind record id like below. It will solve the issue.
var cust = new DynamicsCustomerRecord(new EntityDescription { Id = contactId, LogicalName = "contact" });
cust.SessionName = customerFromCrm.FullName;
CustomerEntity sessionCustomer = null;
sessionCustomer = new CustomerEntity(contactId.ToString(), cust, "<CustomerID>1<CustomerID/>", false, this.ApplicationName);
sessionCustomer.IsNewCustomer = true;
// Start a new session
OpenSession(sessionCustomer, Guid.Empty);
Let me know if you have more questions.
Sreeni Pavalla