Hello rik272,
It looks like no one has responded to your question. Here are a couple of things that might help others answer your question:
-What software version are you running on your iPhone?
-How long have you had this issue?
-What type of calendar are you using? For example, Outlook, or iCloud?
-How far back on your calendar are you trying to search?
-Have you tried any troubleshooting steps on your own? If you have, what were they?
The more information you provide, the better chance the community will be able to offer some additional guidance.
Have a good day!