Maybe a little bit offtopic: Help Heroes 4 Mission 2

[Ben Kingsley]

Sorry when I am offtopic but maybe someone can help me:

I am playing the 2. human mission and I have to fight with the final hero. This final hero is hidden in a big fortress (at the right-down corner of the map), which will only open when I visit the keymaster. The color of this fortress is purple and I have visited the purple keymaster already. He sais: "I have give you the purple key already, now leave!" But when I go to the fortress where the final hero is hidden, it sais: "To open this gate, visit the purple keymaster". I am getting worried about this! I have been walking 10 times between the keymaster and this fortress, but I can't get in in! No way! Is this a bug? Please help...