I only played it once, but the evil side also lost there. Funny thing is, the goblin king got in at the first turn, and still the evil side lost. The goblin king although really crushed the dwarf on one of the bridges, and thus if the goblins had 1 more turn they would've run.
Maybe try and just have the goblin king automatically come in at the first turn. I don't think the scenarios are THAT well balanced, coz, with the first scenario the goblins always win, the dwarves can't make it to the other side within the turn limit.
Above all, i belive the scenarios are made to learn the rules a bit at the time, while providing fun scenarios. I think
They also state in the scenario book that if you feel either side need a little more help, try and alter it a bit. I think if you let the goblin King enter automatically at the first Turn you will see a close fight that's what i saw at least
