Problems with rppppoe gui

[syd2o2]

I just installed Ubuntu 7.04 beta, and I have a problem with rppppoe.
When I type tkpppoe in terminal I get:
syd@syd:~/Desktop/rp-pppoe-3.8$ tkpppoe
exec: 24: wish: not found
syd@syd:~/Desktop/rp-pppoe-3.8$

After the initial installation of Feisty I installed build-essential package with
sudo apt-get install build-essential
Tnen downloaded rppppoe 3.8 and typed from terminal
sudo ./go-gui
It compiles and installs, but when it's supposed to start gui it fails with that error.
This same process worked and still works on another computer with Ubuntu 6.10.
I need to use rpppoe with gui instead of the default pppoeconf because I often need to switch between two different providers, and it's a lot quicker and easier with a gui.
What am I mising? Can anyone help?