Need help to configure a WiFi router

I need some help to configure a WiFi router SMC Barricade SMCWBR14-G2, my problem is this!

When I go on the administration page for configuring WIFI to the place where you must configure the WEP key, I enter a zone or the pass-phrase, if I type a sentence of more 5 characters, and then I try to access the network it throws me ... reading the network address does not like the WEP key entry was false ...

if in the sentence I pass is a word of 5 characters it works!

Can someone tell me how to configure the WEP key please?

Thank you

It works with 5 characters, it means only that you connect to the router?
If that leaves like that, the main thing is to connect.
For against, with 2 bullets question: we gave you or you have purchased a vacuum in the attic?
He wpa your router?

yes it is WPA/WPA2

I bought it to replace the WIFI the Sagem livebox which does not connect more than 20 minutes in surf or on MSN does not reflect, but to download or connect to game sites is cast on every 20 minutes

For the story of five characters I know I can leave it like that, but this level is safe enough?