Background color gone with alpha matte

[RunninBlooper]

So I´m very new in this program and i dont really know what I´m doing so this might be a very simple answer...
I wanna make an animated follow button for my stream that gets "clicked" and shrinks from a rectangle to a square so that the follow text disappears and only the heart at the beginning stays within the button.
i´ve found out how to make the "follow" text disappear with the shrinking background. but the background loses its purple color when i do that.. i tried to copy the background so that one is used as the border for the text and one for the color but it does not work... what am i doing wrong?

[Rick Gerard · Accepted solution]

Your Layer 3 is a shape layer used as a track matte for layer 4. That means layer 4 will use layer 3 to create transparency. If layer 4 is a text layer. Both layers 3 and 4 have keyframes at the same time but I don't know what they are doing or how they are moving. There is nothing below the text layer (Layer 4) so I don't know where the background color is supposed to come from. If you have set your composition background color to anything but black it won't render as that color with most codecs. If you need a colored background you need a background layer. 

We need a more detailed workflow description and we need to know where the purple background is coming from. You should also select all problem layers and press the 'u' key twice to reveal all modified properties so we can see what is going on with the layers. 

Please embed your screenshots in the future by dragging them to the reply field or using the toolbar. The Drag and Drop here field is pretty useless. I don't know why it is even there. 

[RunninBlooper]

Thank you very much! You actually answered my question... Layer 3 was supposed to be purple but as soon as its used for a "shape-window" (dont know the acual word) it obviously loses its visibility! So when I tried to copy layer three and put it below everything - the eye symbol was off...
sometimes the answer is so simple - thank you very much for your answer