A couple things you might try.. remove the card carefully and check the position of the "lock" tab. Make sure it is fully in the unlocked position - not locked or a point between the two positions. Reinsert and try again.
It sounds lie you're using a card reader to download the pictures - try formatting the card while in the card reader via computer. The card should be completely empty when the format is complete. You can even try copying files to and from the card to make sure its ok and format again. When complete, try again in camera.
If the problem persists, check to make sure the card is on Nikon approved memory card list for use with the Coolpix L1 (provided below):
The following is a list of approved memory cards for the Coolpix L1
digital still camera. These cards have been tested and approved for use
with the Coolpix L1.
The L1 uses SD (Secure Digital) memory.
64MB, 128 MB, 256MB, 512MB, 1 GB, 256MB*, 512MB*, 1GB*
- 64MB, 128MB, 256MB, 512MB, 1 GB, 128 MB*, 256MB*, 512MB
- 64MB, 128MB, 256MB, 1 GB, 256MB*, 512MB*, 1GB*
* - Cards rated for 10MB/s (high speed) Other cards have not been
tested. For more details on the memory cards listed above, please
contact the manufacturer.
The list came direct from Nikon Support
. Other cards may work, but only those on the list are approved. Successful use of other cards can not be guaranteed.I hope this helps!