well, i still do not know what your problem is, I am using it right now too . Anyway, I can give you a little thing that i said to help ppl like a month ago. Here it is:
go to the folowing link to help for anyone!!! it works for me awsome!

http://www.i-hacked.com/content/view/195/62/

"

Ok well that all should work, now when using the TightVNC on ur pc make sure that there is a short password set and that you can control your mouse from the psp only. I still do not know exactly what your specific problem is though try reinstalling it and see what happens (on pc and psp)

O yea, make sure that WLAN Powersaver is OFF! it works on 2.6 if it's OFF!

i made a lil video of vnc workin on my psp if anyones interested =)

http://video.high-flow.com/cd-pspvnc.mov

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I have this up and working well on 2.71SE Firmware on my home wifi connection.

I would like to be able to view it from an external connection i.e. works wifi to home. Is this possible if so how do I set it up? I already know my home external ip address but can't seem to get it to connect

I use no-ip.org to dns my connections through my router, even if my ip changes. Instead of using my ip address, I use something like inottellingyou.no-ip.info, and that connects back to my computer.

::::Edit::::

Never mind, PortableVNC does not support dns-ing. But just about everything else does, including iRShell.

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Thats pretty amazing! Hopefully it will come to 2.7-2.80.