AirDrop does not work on my iMac
I wanted to transfer a file from my iPhone to my iMac using AirDrop, but it is blank in the Finder.
I only have the following: "AirDrop lets you share instantly with people nearby. To share with someone using a Mac, ask them to go to AirDrop in the Finder."
I know that both Bluetooth and our WiFi are on.
Also, both the iMac and the iPhone are on the same WiFi network.
My iMac was bought in July 2011 and the OS is macOS Sierra.
Is my problem related to the OS, or something I did not configure?
Thanks for your help Apple Community.
Phil
iMac 21.5", macOS 10.12