Compilation error

Server Error in '/' Application
Compilation error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.
Compiler error message: CS0246: The type or namespace name 'Logic' could not be found (are you missing a using directive or an assembly reference?)
Source error:
Line 18: // SqlConnection _con;
Line 19: // SqlCommand _com;
Line 20:  Logic _Bl = new Logic();
Line 21: protected void Page_Load(object sender , EventArgs e)
Line 22: {

Source file:  c:\inetpub\vhosts\candaztech.com\httpdocs\Contact.aspx.cs    Line: 20 

Microsoft (R) Visual C# 2005 Compiler version 8.00.50727.3053
for Microsoft (R) Windows (R) 2005 Framework version 2.0.50727
Copyright (C) Microsoft Corporation 2001-2005. All rights reserved.

warning CS1668: Invalid search path 'C:\Program Files\SQLXML 4.0\bin\' specified in 'LIB environment variable' -- 'Access is denied. '
c:\inetpub\vhosts\candaztech.com\httpdocs\Contact.aspx.cs(20,5): error CS0246: The type or namespace name 'Logic' could not be found (are you missing a using directive or an assemb

Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082