Connection Issues with Macbook, iMac, and Apple TV 3

I have an Apple TV 3 (ATV3) and my iMac connects via Home Sharing just fine, but my MacBook running 10.6.8 doesn't show up, nor does it recognize the iMac in iTunes. All devices have Home Sharing turned on using the same AppleID. Any thoughts as to why my Macbook seems to be the odd one out?