WPF: Project doesn't find its own Classes ("tag not found in namespace")

Hi there,

I've got a problem that's driving me crazy:

c# WPF Custom Controls Project (NET 7), Base Namespace "UserControls". All the controls, styles and Converters existing in the project are in that namespace (I tripple checked, it's the only namespace used). All the controls and Converters are public classes.

In the project, there is a Class named "EqualityToBooleanConverter.cs"

Additionally, there is a Style file called Button.xaml. I need to use the aforementioned converter here, so I am referencing it like this:

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:local="clr-namespace:UserControls;assembly=UserControls">

    <local:EqualityToBooleanConverter
			x:Key="ETBConverter" />

Intellisense does find the Namespace "UserControls", in fact, the namespace declaration AND the ressource declaration was done using intellisense.

BUT as soon as I compile the project, the following error pops up:

MC3074 - type "EqualityToBooleanConverter" does not exist in "clr-namespace:UserControls;assembly=UserControls"

I just don't get it, as I said, all the files are in the same project, and they are - as of now - all using the root namespace "UserControls". Everything is fine until I start compiling.

What I have tried so far:

• removing the "assembly"-part of the namespace-declaration
• changing the compile target from AnyCPU to x86 and back
• cleaning the solution
• creating a new solution, and re-adding all the files to it

Also noteworthy: The same problem occurs when I try using one of the Usercontrols in that project WITHIN the project itself (like: creating a Window.xaml, defining the local-namespace, and trying to add the control leads to the same error as soon as I compile).

I don't know what else could cause this...does anyone have any idea?