Compiler Error Message: CS0246: The type or namespace name 'CartelServices' could not be found (are you missing a using directive or an assembly reference?)

I am hosting my web application into godaddy.com.

If i write whole code inside single page then it works fine but if i make it modular and try to use namespace my class library then this error comes.

Error on this page : http://cartelsolution.com/4.5.1/cartelsolution/school/Login.aspx

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 'CartelServices' could not be found (are you missing a using directive or an assembly reference?)

Line 11:     public partial class Login : System.Web.UI.Page
Line 12:     {Line 13:         CartelServices.CServices services = new CartelServices.CServices();Line 14:         protected void Page_Load(object sender, EventArgs e)
Line 15:         {

If i use my namespace by using CartelServices; then i get same error.