I have the following class:

[MetadataAttribute]
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public class ModuleActivationButtonAttribute : ExportAttribute
{
    public Enum TargetRegion { get; set; }

    public ModuleActivationButtonAttribute(Enum targetRegion) : base(typeof(IModuleActivationButton))
    {
        TargetRegion = targetRegion;
    }
}

The class compiles fine, but when I decorate my property with it:

[ModuleActivationButton(Regions.Tabs)]
public IModuleActivationButton ModuleActivationButton
{
    get { return new ModuleActivationButton() as IModuleActivationButton; }
    set { ModuleActivationButton = value; }
}

public enum Regions
{
    Content,
    Tabs
}

The compiler spits out:

Error 1 An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type C:\...\Manpower4U.Modules.Home\HomeModule.cs 28 33 Manpower4U.Modules.Home