Sql server stored procedure is stopped while running from front end in ASP.NET

I have a sql stored procedure to upload the group of files. when I run that procedure from front end half of the files are uploaded and the procedure is stopped suddenly. but when I run it from backend its running.I don't know the exact reason. Please can anyone help me.(Note: I am using IIS to run the application)

DAL.ExecuteDML("dbo.Proc_Upload_Batch", CommandType.StoredProcedure);

public int ExecuteDML(string ComandText, CommandType Commandtype, params SqlParameter[] parameters_values)
       {
           com = new SqlCommand();
           if (Session["Transaction"] != null)
           {
               com.Transaction = transaction;
           }
           com.Connection = GetConnection();
           com.CommandText = ComandText;
           com.CommandType = Commandtype;
           com.CommandTimeout = 0;
           foreach (SqlParameter param in parameters_values)
           {
               com.Parameters.Add(param);
           }

           int rowsaffected = com.ExecuteNonQuery();

           com.Dispose();
           return rowsaffected;
       }