If no one can access your triggers and you can't send then you either have the port(s) blocked or else your IP is not set correctly in mIRC's options.
To check your IP: Alt-O > Connect > Local Info. The IP listed should be exactly the same as what you see if you /dns yourself (type /dns yournick in a channel/query/status windows). If not, change it to the correct info.
For ports, check what port(s) you are set to use in mIRC: Alt-O > Connect > Options > Advanced - Make sure DCC is checked and look at the port(s) listed. You may have the really large default port range (1024-5000 or whatever it is). You can change it to anything and usually only need about 20 ports in the range. Once you pick the ports, make sure those same ports are forwarded in your router (TCP, not UDP).
www.portforward.com is a good place for help with your router if you don't know how to do it. Also, make sure you don't have a firewall blocking ports (like Windows Firewall). If you still can't get it to work, try different ports... sometimes a port will conflict for one reason or another. The port range you choose should be 1024 or higher to prevent some possible conflicts with commonly used ports.
Finally, you can use passive connections in mIRC's settings (or Reverse DCC from Invision's settings) to connect in reverse... this requires the those who connect must configure their routers/firewalls correctly to connect to you, so it works but not for everyone. It's a last resort method only.
Btw, I deleted your other post. Please don't make duplicate posts.
You can find me at #Invision on irc.irchighway.net or #OldGames on irc.undernet.org if you need me for anything.
