Alpha Matte on Illustrator layer

[kristofferh89]

Hi there, relatively new to After effects, so sorry if this has been posted before;

I´m trying to get my composition in the bubble by using Alpha on the Illustrator layer that is the bubble , but it seems that the only TrcMat that gives somewhat wanted result is the Luma Matte.

When I try to use Alpha the bubble is all white, and not showing the comp. I´ve tried changing the mask from Add to subtract, with and without inverteded.

What the duck am I doing wrong? These are my settings. 

[Jose Panadero]

I think the layer order is incorrect. Track mattes need to be always over the layers that will be masked. So the correct order is Bubble on top and the "Scene I want to alpha" below, and select the alpha matte option for the "Scene I want to alpha".

[kristofferh89]

Now I feel like a total noob, it was as simple as that, thank you!

[Roland Kahlenberg]

Other than Jose's instruction, you may want to look at using Effect>Channel>Set Matte. The Set Matte effect doesn't require the two involved layers to be in precise, relative positions in the Timeline.