Passing a taxonomy term from Panels to View using relationships and Views Pane

Sorry if this is duplicated, but I've been searching&fighting for hours.

I want to create a very simple panel that shows:

- A node (node ID parsed from the URL)
- The forum topics that share the same category term than the node.

So if the node 189 title is "Apple" and belongs to the category term "Fruits", I would like to browse to:

http://www.mysite.com/?q=test_panel/189

and see

- The node "Apple"
- All forum posts on "Fruits"

What I did:

1. I have created a Views with a Forum Topic Node Type Filter and a "Taxonomy: term name" argument.

2. I have created the Panel.
- In Context, Arguments, I have set a "Node ID" Argument.
- In Context, Relationships, I've added a "Term from Node" relationship. (Vocabulay: Forums)

3. I have created the Views Pane
- Argument Source: from context
- Required Context: Taxonomy Term

4. I have set the Panels Content
- The node on the left.
- The view on the right

What happens:

In http://www.mysite.com/?q=test_panel/189 only the node is shown. However, the Panel works fine if I use a "Fixed Argument Source" instead.

What am I doing wrong?