I hate when I have this problem. It's been a few weeks for me too!
Ok seriously. How long has it been on tap? It might just not be fully carbed. If you've left it under pressure for a week or longer and you're still not getting any head you might be dispensing with too little pressure. Some brews just don't have a lot of head though no matter what you do. You could look at your recipe and see if there is room for something to enhance head retention.
It's ironic too because I brewed this beer the weekend my fiance left for Gabon for 4 months.
It has only been in the keg for a couple days but past brews I've made would develop a nice, frothy head even uncarbonated. So recipe then? Are brown and victory malts prone to poor head development?
All things are better with time... carbonation and head. Seriously, who would turn down 5 min of head vs 30 min of head. Patience grasshopper! (think of baseball, it will postpone premature pours).
Head is fleating sometimes. You get it one week and none the next. I haven't had good head for weeks. My beer has a lot of foam though, so I can't help you there.
I try to bring my beer flowers at least once a month. That helps! Also, beer gets jealous so you have to make sure you give it ample attention and love.
-Jefe-