Transparent symbol? Why only one layer of symbol transparent?

I have a symbol containing some layers.

Now on the main timeline of my project, i want that symbol to be, lets say 50% transparent. I added a transparency module, and now i see my drawing layer with the symbol on it, and as a child of that i have a transparency ‘layer’.
But only one layer of the symbol becomes transparent. The rest stays 100% visible.

Why is this and how can i solve it?
I want the whole layer /whole symbol to be transparent.
(and animate that over time, but thats step 2 ;))