Tk_Init failed: bad screen number "0"

I just compiled insight for mips-elf but I'm unable to run it though. This what it looks like:

cayman:~# /usr/local/insight-mips/bin/mips-elf-insight
Tk_Init failed: bad screen number "0"
cayman:~# /usr/local/insight-mips/bin/mips-elf-gdb -w
Tk_Init failed: bad screen number "0"

I guess tk can't create any windows which I can't understand because I can start other windows from my shell with, for example, executing "xterm" which brings up a new window with a shell. Should I set some other environment variables other than DISLPAY?

Can anyone please give any ideas on what's wrong?