dedicated server HELP

So my brother works for a internet company (whole family actually) he got to make a dedicated server, and he said he downloaded the server files from minecraft.net
he gave the IP and port to me . but when i connect it says loggin in then my minecraft crashes

i ave my own server (not dedicated) and i can connect perfectly fine to my server and people in the UK and etc,
what could be the problem that if i try connecting to him , my minecraft crashes???

 

It just crashes and does not report any errors?

 

yes correct, lately it does that, just crashes and closes. do u no the problem? of why it crashes and wont allow me to connect?

 

Hmm, yes it closes when it crashes, but aren't there any errors in server.log file?