Error connection C# in-quickbooks-2003

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C#

Quickbooks

I need to connect to QuickBooks Enterprise 2003 and the following code does not accept majorVer as 2.1 which support usin AppendInvoiceModRq and AppendDataExtModRq so i tried to change majorVer to 2.1
after that i have error (It must be cannot convert from 'double' to 'short') my problem that majorVer 2 not support what i want to do but quickbooks 2003 SupportedQBXMLVersion v 2.1 that's code to connect

private static void OpenConnection(short majorVer,short minorVer,string companyPath) {
        SessionManager=new QBSessionManager();
        //Create the message set request object to hold our request.
        RequestMsgSet=SessionManager.CreateMsgSetRequest("US",majorVer,minorVer);
        RequestMsgSet.Attributes.OnError=ENRqOnError.roeContinue;
        //Connect to QuickBooks and begin a session
        SessionManager.OpenConnection("","Open Dental");
        ConnectionOpen=true;
        SessionManager.BeginSession(companyPath,ENOpenMode.omDontCare);
        SessionBegun=true;
    }

Any help is highly appreciated

i try to doing update to invoice using this code

public void updateInvoice(string invoNumber)
       {
           OpenConnection();
           majorVersionQB = Convert.ToInt16(QBFCLatestVersion(sessionManager));
           requestMsgSet = getLatestMsgSetRequest(sessionManager);

           requestMsgSet = sessionManager.CreateMsgSetRequest(countryQB, majorVersionQB, minorVersionQB);
           requestMsgSet.Attributes.OnError = ENRqOnError.roeContinue;

           IInvoiceQuery InvoiceQueryRq = requestMsgSet.AppendInvoiceQueryRq();
           InvoiceQueryRq.ORInvoiceQuery.RefNumberList.Add(invoNumber);
           InvoiceQueryRq.OwnerIDList.Add("0");
           InvoiceQueryRq.IncludeLineItems.SetValue(true);
           InvoiceQueryRq.IncludeLinkedTxns.SetValue(true);


           IInvoiceMod updateInvoiceModRq = requestMsgSet.AppendInvoiceModRq();

               updateInvoiceModRq.Other.SetValue("hi");
               updateInvoiceModRq.EditSequence.SetValue("1640351207");


               IMsgSetResponse responseMsgSet = sessionManager.DoRequests(requestMsgSet);

               IResponse response = responseMsgSet.ResponseList.GetAt(0);


           CloseConnection();







       }

i got error

System.Runtime.InteropServices.COMException: 'This request is not supported in the specified qbXML version.'

What I have tried:

I need to connect to QuickBooks Enterprise 2003