Right click procedure place object destroys current block

I tried to use 'if air at x y z = true do (events)' as a modifier to make sure the space was empty, but then it didn't work at all.

There are three of us looking at this, and we aren't sure what else to do.  When the plant item is placed by the seed it should not destroy a furnace, stone block etc etc.. it should be only able to be put in a blank space.  How do I do this with the world info available?