Hello fellow gmail I am faced with a rather difficult problem. I believe that after only 4 months my pcs are starting to become bored of our campaign. While I have not heard any complaints I feels that many harbor displeasure and I am trying to take steps to fix this. I have started by final planning an end goal (make and lead a warband, the leadr will become a space marine in the following campaign) I still am worrying day and night about the enjoy ability of my GMing. I might just be paranoid but I'd rather be safe than sorry. 

Have you considered just asking them what they want from the game?

Black Crusade generally works best when the players dictate the type of game. Would they like to infiltrate the Imperium? Topple planetary governments? Overthrow other chaos warlords? Unravel warp mysteries? Fight xenos?

When you say that you've designed the end goal, that sounds like the players have comparably little say in which direction the campaign develops. Why not throw six to eight plot hooks into your next game that could lead towards any number of overarching adventures and then see which one they bite on?

Seeing how you got the impression of them being bored, does this apply to the whole game or do they seem bored with a specific aspect of the game ?

Do you have the focus more on the roleplaying part (as in social interaction) or combat ? Does it seem fights bore them or do you have a lot of intrigue and they feel the game could move at a faster pace ?

Do they enjoy combat in general ? Or do they maybe enjoy only fleshed out opponents as opposed to fighting hordes ? Do you feel that you are spicing up combat with enough flavor text and the gory details of their opponents demise or is it just sterile numbers and game mechanics ?

Do your roleplaying challenges have a real meaning for the outcome of the campaign ? Do your players seem motivated to achieve the campaign goal you envisioned, or does it seem they'd like to pursue an entirely different goal ?

Tell us a bit about how your group plays, it will help to nail down the problem if there is one. And in my experience, a GMs instincts on this are rarely wrong.

yep speak to them.

An easy way is to ask them how they see and hope their character progresses. You can then use their goals as starting points for adventures. And they can also give hints as to what kind of campaign they may be wanting.

Then having started the discussion on their characters Follow it up with a couple of questions about what aspects of the game they like or dislike.  That way you don't start with a what's wrong/right question which could make them uncomfortable if asked first.

I just answered a post called "tips for a new gm" with some general advices on GMing, but i didn't manage to link it, but maybe the answers in that post could help you as well: http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=270&efcid=46&efidt=708124&efpag=0#719139