Welcome to the “Bell Talk” discussion board. Can you post a couple of photos of your bell to aid in being able to answer your question. How long have you had the bell and did you buy it new? If you acquired it as a used bell, at this point I would guess that your bell at one time had a clapper attached (more than likely a clear plastic disc with a bead attached that was glued into the bell )and that it fell off and got lost.
Often times if a glass bell is delicate (especially “English Wedding Bells”) and there is a possibility that a clapper could damage/crack the bell, then the clapper is intentionally left off or at least is issued with a removable one. Still a bell…just a pretty silent one.
Thank you for your comments. Sadly, I can’t post a photo because I gave the bell away to a dear friend. I bought it used, on Ebay. Judging from the script style of the etched word “Nisswa”, I suspect it might date from 1890-1910. Your suggestion that there once was a clapper attached to a glued-on disk sounds plausible.