Error with C# Partial classes

Question

I am using partial classes to split some functionality between 2 files, but I am getting an error. What am I doing wrong?

A1.cs:

private partial class A
{
    private string SomeProperty { get { return "SomeGeneratedString"; } }       
}

A2.cs:

private partial class A
{
    void SomeFunction()
    {
        //trying to access this.SomeProperty produces the following compiler error, at least with C# 2.0
        //error CS0117: 'A' does not contain a definition for 'SomeProperty'
    }
}

Answer 1

Are the two partial classes in the same namespace? That could be an explanation.

Answer 2

Same answer as @Andrey K but in simple terms

Set the build action of all your partial classes to 'Compile' using the 'Properties' windows of each of those files