Unable to set Orderdate in SalesOrder in Sage100

Hi All,

I am trying to set the value of  OrderDate while importing Sales order. Record imported successfully, but order date does not reflect in Sage100. It remains the same as previous order date.

I don't know where I am wrong. Please help me. Do I need to set value from ERP? How to change AccountingDate programmatically. 

Given below is my code.

if (objCreateNewSalesOrder.OrderDateSpecified)
{
       //setValueString<DateTime>(retVal, oARCustomerEntry, "OrderDate$", objCreateNewSalesOrder.OrderDate); ToString("MM/dd/yyyy hh:mm tt")
       setValueString(retVal, oARCustomerEntry, "OrderDate$", objCreateNewSalesOrder.OrderDate.ToString());
       
}

private void setValueString<T>(object retValue, DispatchObject oARCustomerEntry, String strFieldName, T strValue)
{
    try
     {
          retValue = oARCustomerEntry.InvokeMethodByRef("nSetValue", new object[] { strFieldName, strValue });

      }
}