Air won't automatically join my WiFi

My Mac Book Air won't automatically join my WiFi system after it's been asleep. I need to manually click on the WiFi Icon at top right of the screen, wait a couple of seconds for the available WiFi signals to come up and then click on my Network. I recently upgraded to Lion OS X across all three Apple Computers (MacBook, iMac and the MacBook Air). The other 2 machines join automatically. The settings in System Preferences/Network/WiFi are the same. I've rebooted the Air several times. I'm new to the forum and my apologies if I haven't posted this in the correct location. Any advice would be much appreciated. Robert

I've moved your post to a more proper forum; please be sure to check the forum descriptions to find the best place to post.

By posting in the right forum you help people not only find your question faster, but it helps others looking for the same information in the future.

Thanks for understanding!

same issue on my MBA...

i have been experiencing the same issue intermittently. i believe this is an hw issue rather than sw as i have only experienced it on this MBA (2.13GH, 2nd gen) and have seen it happen on both leopard and lion.

additionally,
- i have my network settings set to automatically join "known" networks
- i have reset both my wifi port and my wireless rtr

this only happens when bringing the mac back from sleep mode and i would estimate that it occurs approximately 20% of the time.