I am using AE cc2015. I have successfully alpha matted a jpeg file to a text layer and am unable to alpha matte the same jpeg to a different text layer. Any help is appreciated. I have pasted a pic of what I am exactly trying to do. So "hello" and "world" are alpha matted to my jpeg and "my" is not. I hope this helps.
Please don't crop your screenshots and please reveal all of the modified properties of the layers you are having problems with. We can't see what's going on.
If you want to use the same layer as a source for a track matte for more than one layer then you need to duplicate the layer or select all of the layers you want to use as a track matte, pre-compose them and then use the pre-comp as a track matte.
Alpha Matte is a nonsense term when you are referring to AE and track mattes.
To learn more about track mattes and how to use them type "track matte" in the search help field at the top right corner of AE and read up.
Thank you for your support @Rick Gerard. I will try it out and let you know if I succeeded.
I took all of your advice and it worked.