HomeGroup - Difficulty with adding 2nd Desktop to Network

I have two desktops running Windows 7 64-bit on a home network with a Linksys E3200 router. All seems to be running normally on both desktops and on the network. I’ve established a HomeGroup on one of the desktops , but cannot join with the other desktop. I have gone through the list of items in “Why can’t I join a homegroup?” to no avail. On the “Network and Sharing Center” windows of each desktop, the network name is identical.

Any version can join a homegroup but only Home Premium or better can create a Homegroup, so first off, is at least one of your machines Home Premium?