My friends con't join my tekkit server

[perry04]

So i have a normal mincraft server that i run on my pc and my friends can assess that, but when i downloaded the server for tekkit and run the server ( I did port forwarding and they can assess my normal server) it doesn't show up for them there is just an x throw it. Do i have to do a different port forwarding for this server? I can join the server justfine. When I do run the server i do get two warnings they are 1) {Configuration for mod_computercraft.enableAPI_http found value 0 outside acceptable range 4.9E-342,1.7976931348623157E308} 2) {could not get information about this Craftbukkit version; perhaps you are running a custom one?: FileNotFoundException.} I dont know what they mean or if they have any effect on if my friends can join? what can i do to get them to assess my server?

Also to note when I downloaded the tekkit launcher and created my own world it got a warning on the bottom left that say something along the lines of (you are 5 version behind the r17 and this message will not show up after 1 more log in) i didnt copy it down because there wasnt any problems that i could see. I dont know what this mean as well?

[Brentnauer]

The second bit is just because the ambient noise mod is outdated, you can ignore that.

Not sure about the first part though. If it works for Vanilla and not Tekkit I'm at a loss unless it's using a different port.