how to make SP filter using blending mask?

currently, I'm making some substance filters. I'm watching this page(https://substance3d.adobe.com/documentation/spdoc/channel-specific-filter-140902406.html) for reference. 

when we use substance painter, we usually add the mask to a layer or folder. 

I like to read the mask as input. So I tried to use blendingmask as the usage and identifier. 

But the filter doesn't even work as a filter. I mean, after I clicked 'add filter' and chose the filter I made, the filter box remained empty.

I attached the .sbs file. Please check the file to shoot the trouble.