Adding a wireless AP

Hello all,

I am having real trouble getting my wireless AP working as I would like it.  As a disclaimer, I'd like to say I'm totally new to this networking magic - I've always let my ISP's router do everything for me.  I decided to jump in the deep end and install UTM9 on a low power box with 4 nics.  Everything is working ok and I have wireless so long as I plug the TP-Link AP into my switch.  However, I'd rather have it running through the UTM9 box and this is where my problem lies.

My current situation is the AP is being handed an IP by DHCP, I can ping it from a PC on my network and from the switch itself.  Devices can connect to it, however there is no Internet.  Neither does it appear anywhere in the Access Points overview.  Also, I cannot web into it.

I've tried lots of different settings, but nothing seems to make any difference.  I've Googled the hell out of it, but most guides are for Sophos AP's which just seem to "appear" in the Access Points overview as soon as you connect them.  Ideally, I'd really love a step by step guide on how to configure it.

If anyone can offer some pointers or links, I'd be very grateful.

Thanks!