Style Trigger to Apply another Style

Question

I am sure this has been asked before, but I haven\'t had an easy time figuring out how to phrase the query.

I have this style;

Answer 1

Styles cannot be set from a Setter within the Style, because then essentially the first Style would never exist at all.

Since you're looking for a Validation style, I would recommend looking into Validation.ErrorTemplate, although if that doesn't work you can change your trigger so it modifies specific properties such as BorderBrush instead of the Style property