I had a similar problem with my Orinoco silver too. Struggling for a while and finally solved after I enter the correct ESSID and encryption(WEP) key.

My experience is that the ESSID must match the one one the router, either though the manual hint that empty("") means any which should work. I may write to the author to clarify this.

The WEP key is also tricky as it needs to enter in the form of "sxxxx", the xxxxx is the 40 digit one, as one used in windows.

Hope this help.