How come my psp detects my router but it dosnt connect to it?

May be...

OK so i got a new psp this week and i am quite new to it i have custom firmware 3.80 m33-5. I want to go online but how come my psp cant connect to it. It is WPK encrypted but even before i encrypted it it still had this problem it would show up and i could select it and test it and it looks like it is going to work but when i accually connect to it, it dosnt work how can i fix it? Oh and one more thing my router is wireless G.

It should work, but since it is encrypted you have to enter the password that you used to lock it up. If that doesn't work then something is wrong with your router.