Autoreceive might be turned off. Holding the lower right hand 'SEARCH' button down should force a manual receive, a quick press should tell you when it was last synchronised. In this mode pressing top left will bring up 'RCV' and lower right toggles autoreceive on and off.
Here's the manual, which explains it a lot better than I do:
https://support.casio.com/storage/en...009/qw3089.pdf