Wireless Laptop will not connect to a secured network

I have an Acer laptop w/ Windows 7 Startup. I want to create a "secured" network by turning on the MAC address filter on the wired/wireless router but the laptop will not connect to the network. I have put the laptop MAC Addr.
into the filter and turned on the "only allow the following MAC addresses to connect" sub-filter. What should I do now? - Lee P.S.-When I first connected to the un-secured network it ask me for a "key ". Now it's almost as if it is "connecting automatically" with NO questions.

 

As you will read at the end of this guide MAC address filtering is no longer considered secure, but this guide should help you check where you may have gone wrong, if you wish to use it.

http://www.timeatlas.com/Term_to_Learn/General/MAC_Addresses_and_Filtering

This guide for windows 7 will help you to make your network secure with other methods that are more up to date.

http://www.dummies.com/how-to/content/set-up-a-secure-wireless-network-in-windows-7.html