Sometimes it takes longer to get all the gunk out and sometimes in my case it wasn't only in the bottom of my hens foot but had moved to between her toes. Inspect the whole foot for other areas not the black plug persay but a bubble of some sort anywhere on the rest of her foot. That too needs to be cut open to get to the plug as well. If this didn't work for you then you didn't get it all out and it kept coming back.