[Boost-users] d_ary_heap_indirect problem

I am trying to use d_ary_heap_indirect. I was able to create an object of the queue, but I can't push a vertex into it. Here is what I tried: http://programmingexamples.net/wiki/CPP/Boost/BGL/d_ary_heap_indirect I get a "no match for operator[]" error on the last line (the push()). Can anyone see what is wrong with that example? Thanks, David