Hi. My name is*****'m a camera repair technician with over 20 years in the business and I'll be glad to help you with your question today.
The most likely cause for this is bent or broken pins in the CF card reader.
Using a flashlight, look at the bottom of the card slot for damage. If there is, the pin set will need replaced. This really isn’t a user serviceable problem and should be repaired by a qualified technician. You may want to check locally for a camera repair shop in your area, or, if you need assistance finding a shop, please let me know and I'll locate one for you.