Your problem is that your camera only takes standard SD cards up to a maximum of 2GB
. The card you have bought is likely to be a 4GB SDHC model. SDHC is a later development of SD; SDHC compliant devices can still use older SD cards, but SD-only devices cannot use SDHC. This is a hardware limitation so there is no way at all to use an SDHC card in your camera.
Note that if your 4GB card is definitely an SD and not an SDHC then it's still incompatible with your camera: very few standard SD devices were ever made with the firmware and hardware to handle the different memory addressing architecture used by the larger capacity card. Some cameras did have firmware updates to allow the larger SD card to be used, but yours is not one of them.
Your only fix is to sell your card (or keep it for another device) and to buy a regular SD card no larger than 2GB maximum capacity.
I trust that my reply has answered your question fully, please take a moment to rate my answer.