I know a lot of people get stuck here. I played it years ago and vaguely remember the same problem but managed to get the right stuff to throw. Here is what the walkthrough said that I used:
At this point you must have the following in inventory:
shield, helmet, arrows, fairy dust,sword, hay, book, bonding plant, fear necklace, knife, tele-orb, thermozz, illuminite, mirror, wire, zorkmids, matches, box, talon,, puzzle, metal thing, boos keys, flask, bow,rope, witch stick, carrots, rag, gold key. At this point the instructions are to start throwing everything into the fire - when enough objects are thrown in the bridge will raise.
I don't know if you need all this stuff, if it even makes a difference (the hints book I have said you have to have at least 7 inventory objects to throw in - just not which ones) - but I had all of it and I made it across okay.
Dark Side : Risen
I can only please one person a day. Today isn't your day. Tomorrow's not looking good either.