Stored procedure with referenced linkedserver - sql-server-2008

Question

I am fighting with stored procedure with referenced linkedserver. Linked server is accesible over internet via port forwarding - so no VPN, LAN.
Servers are on both sides MS SQL SERVER 2008 EE v. 10.0.5512
Configurations Linked server, DTC:
cannot insert images yet:(
enable promotion of distributed transaction = false
RPC = false
RPC out = false
Network DTC Access checked
Allow inbound true
Allow outbound true
No authentication Required
Stored procedure looks like
CREATE PROCEDURE [dbo].[spSynchronizeArticles]
-- Add the parameters for the stored procedure here
(
#pDebug bit,
#siteId bigint
)
AS
BEGIN
SELECT *
FROM [LinkedServer].[MyDatabase].dbo.Storages
WHERE Storage.siteId = #siteId
RETURN 0
END
As you can see no transaction here. If I am correct the MS DTC is creating transaction every time when the linked server is called.
I am calling this procedure from c# like this
SqlCommand sqlCmd = new SqlCommand("spSynchronizeArticles");
sqlCmd.CommandType = CommandType.StoredProcedure;
sqlCmd.Parameters.AddWithValue("#pDebug", false);
sqlCmd.Parameters.AddWithValue("#siteId", siteId);
SqlParameter returnValue = new SqlParameter("returnVal", SqlDbType.Int);
returnValue.Direction = ParameterDirection.ReturnValue;
sqlCmd.Parameters.Add(returnValue);
using (SqlConnection conn = new SqlConnection(Context.LocalData.ConnectionString))
{
try
{
try
{
conn.Open();
sqlCmd.Connection = conn;
sqlCmd.ExecuteScalar();
return Convert.ToInt32(returnValue.Value);
}
catch (Exception ex)
{
//log exception to file
return -1;
}
}
finally
{
conn.Close();
}
}
}
This c# code is called in infinite while to synchronize data. In same Thread and while there is also another method called which is getting data from file (if any exist) and saving them to local DB.
The SynchronizeArticles method is invoking more often and everything is working, but once the method for getting data from file is called, the SynchronizeArticles always throw this exception
System.Data.SqlClient.SqlException (0x80131904): MSDTC on server
'LocalServer\SQLEXPRESS2008' is unavailable.
The method is using Transaction and looks like
public void FillDataFromViewWithTrans(DataTable dt, string wherePhrase)
{
dt.Rows.Clear();
SqlCommand sql = new SqlCommand(String.Format(#"SELECT *
FROM SomeView
{0}", String.IsNullOrEmpty(wherePhrase) ? String.Empty : "WHERE " + wherePhrase));
using (SqlConnection conn = new SqlConnection(Context.LocalData.ConnectionString))
{
SqlTransaction trans = null;
try
{
try
{
conn.Open();
trans = conn.BeginTransaction(IsolationLevel.RepeatableRead);
sql.Transaction = trans;
sql.Connection = conn;
SqlDataAdapter dA = new SqlDataAdapter(sql);
dA.Fill(dt);
trans.Commit();
}
catch (Exception ex)
{
trans.Rollback();
//log exception to file
return;
}
}
finally
{
conn.Close();
}
}
}
This is just illustration samples :)
Tell me what I am missing.
Additionally I have big troubles with the MS DTC with various errors
From C# code when some users calls the procedure manually they sometimes got exception:
The operation could not be performed because the OLE DB provider
'SQLOLEDB' was unable to begin a distributed transaction.
When I put the begin distributed transaction inside the stored procedure I got:
Warning: Fatal error 8510 occurred at Apr 10 2013 9:07AM. Note the
error and time, and contact your system administrator.
What only helps is the restart of the windows service or the UI application. From the MS SQL management studio the procedure works all the time without problems.
Now I must say I am desperate, what am I missing?
Edit:
int i = 0;
while (true)
{
i++;
if ((i % 9) == 0)
{
//local select with transaction Works all the time
CallLocalSelectWithTransaction();
}
// CallProcedure works 8 times, after first calling of CallLocalSelectWithTransaction
// the callProcedure works no more.
CallProcedure(); // procedure with linked server
}