Mission Question about Defend the wall and others

HI Guys

Lovin the game and have got to lev 7 with my monk. I have a question about missions in general. Do you have to carry them out in any specfic order to get access to the next in line? . The reason I ask is that in Ascalon I can now only get missions about the Frontier gate. When I looked on the forums some folks said that you do the "defend the wall" mission and you are left at the frontier gate. Thats my problem, I cannot seem to find any mission about "defending the walls. I have completed one mission on the Northern Wall and one a Fort Ranik. How do I get to the next missions on both Fort Ranik and the Northern Wall cause my map only shows one sword through the shield on each of these locations so I have missions to complete there huh?

Cheers for the help Folks cause I have been runnin around pretty aimlessly now for about 3 hours :-))

R