Looking for an WPF expert: Solve this and be my adviser/hero

I am an experienced software developer myself (15+ years) and at the moment I am creating a C# MVVC WPF application. It's a project I do together with my business partner, he has the knowledge of the market and I have the knowledge of the software (in general). Sometimes I get stuck and then I wish I had a WPF expert to hand to ask questions. I have good C# skills, but I only have 1 year of WPF experience so far (the begin of this project). At the moment I am stuck on a little problem again and I think this is the right time to find that WPF god where I have been dreaming of for a while now. As a start of our relationship it would be nice if you can take a look at the attached project. It's a working test project, but there is something that I would like to improve. In [login to view URL] you'll find <local:NumberControl Value="{Binding [login to view URL], ValidatesOnDataErrors=True}" /> <TextBox Text="{Binding [login to view URL], ValidatesOnDataErrors=True}" Style="{StaticResource BaseTextBox}"/> Both components are designed to raise an error using the IDatainfoerror interface. The first one is a UserControl that I want to be able to use many times on many different properties. The TextBox binds directly to the object. There are 2 styles defined that show the error (that comes from the model): <!-- works for the TextBox, but should work for the UserControl as well --> <Trigger Property="[login to view URL]" Value="true"> <Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static [login to view URL]}, Path=([login to view URL]).[login to view URL]}"/> <Setter Property="BorderBrush" Value="Orange" TargetName="TextboxBorder" /> </Trigger> <!-- works for the UserControl local:NumberControl only --> <DataTrigger Binding="{Binding Path=([login to view URL])}" Value="True"> <Setter Property="BorderBrush" Value="Orange" TargetName="TextboxBorder" /> <Setter Property="ToolTip" Value="{Binding ([login to view URL]).[login to view URL]}" /> </DataTrigger> At the moment the DataTrigger creates an Error in the Output screen since the Object [login to view URL] is not available at the TextBox. SO: It works the way I want it, but it is just not the right way. I guess that there is something wrong with the bindings because I think that both the UserControl and the TextBox shoud be able to work without the DataTrigger. With other words: Why does <Trigger Property="[login to view URL]" Value="true"> not work for the UserControl? Since this is a typical example of what I get stuck on now and then I like to know if you are able to solve this problem easily. I will be also able to solve this myself, but sometimes it just takes too long because my lack of WPF knowledge. If we start working together I fancy to have a couple of hours a week where we can talk about the project (to improve the technology) or issues that I face. The relationship will be pretty personal (but professional) since I am working for myself and I prefer to work directly with you. Maybe you can also work for the company later (but that still a while to go). I would be super happy if you are solving this problem for me now, but that's not why I am posting this problem here. The reason I post this problem here is that I am curious about your very first view. What do you think goes wrong and how would you tackle a problem like this. It is also here for you to give an idea of what kind of jobs/questions I will typically have. So: If you have the answer pretty fast: And I you understand what I mean with describing the problem: You are my man!!! And for the ones who are curious: The lady is on my profile my mum. So, I guess I'm open for a personal but professional relation ship and let's see where it us brings! Not planned to put my mum on my profile, it's just a recent picture that I like hahaha ;-) Please feel free to ask any questions. I hope we can build up a nice relationship. Cheers Lennart Poot