I use a cottontail probably 70% of the time. The sound you are using is a small part of getting a bobcat.
+100 to that. Seeing them is the hardest part in my opinion. I am convinced that they come in much more frequently than we kill them and never are seen. I have called and killed quite a few but they are very secretive and often just sit out there in the brush watching for a long long time and sometimes just walk off. The hard charging ones are pretty rare but it is great when they come.