[DotNetDevelopment] namespaces - newbie q

[eddiec]

Hi,

I have added a class to a c# asp project and wrapped this in a
namespace

Specifically:
- I added a ClassName.cs file to the project
- The namespace and class are declared in the .cs file:

using System;
namespace my_namespace
{
    public class Class1
    {
        stuff..
        public Class1()
        {
         Constructor..
        }
    }
}

I then tried adding this namespace to an aspx.cs file in the same
project:
using my_namespace;

When I do a build, I receive an error:
'The type or namespace name my_namespace could not be found (are you
missing a using directive or an assembly reference?)'

Can someone please assist me on what I am doing incorrectly

Thank you,

eddiec :-)