I am getting card error each time i put my new sd card in

When your camera was made for SD cards (you did not help us here by entering a brand and model) it could be it won't accept the newer SDHC cards or the SDXC cards.
The SD cards were made up to 4 GB, but now even the 1 GB cards already are SDHC, because they are faster.
Again, when a device is made for SD cards and it did not get an software update, you most likely can't use SDHC cards and certainly no SDXC cards (above 32 GB)
And every card you put in your camera, first format the card in the camera, before using it.

do you mean you switched to a NEW sd card or to a DIFFERENT one you had laying around? sometimes if you put a card into a different device, say maybe a laptop, and you don't go to 'safely remove disc' on the computer it will wreck your sd card when you remove it. make sure you try a new card from a package before you do anything else-if that doesn't work your camera has a problem.

Download frsh firmware from manufacturer, yours may be corrupt and use a NEW sd card, they do develop faults every now and then

Actually, you didn't. You put in a new 4GB SDHC card. The camcorder works with SD cards, not with SDHC cards. You need to use SD cards, 2GB and smaller.

Don't waste your time, t
take it back! You should still be under warranty!

Does it say ERR NO FILE? If so, then read on. The reason you have this error is because you don't have a folder on your sd card named MUSICDAT. Solution:

1. Insert your sd card into computer
2. Make folder called MUSICDAT.
3. Then, transfer all files inside the folder (make sure your songs are in MIDI format).
4. Safely remove your sd card.
5. You're ready to put it in you Casio Keyboard!

If you still get the error, take time to read you manual. Read the "using the sd card" part. The folder name might be different for your Casio Keyboard (because mine's a CTK-5000).
...and IF you still get the error, perhaps the songs you meant in your question are MP3 songs (like the ones you play on the iPod)? Then, that's a different topic... :)
Well then, good luck!

If your new card is actually an SDHC card, your camera can't use it....only SD up to 2GB.

If there are sd card error, you cannot format your sd card. you may get messages like

"No SD memory card inserted" messages appears when using digital cameras,
"A media card hard been inserted that contains errors. Do you wish to repair the Media Card now?"
You can read the files on SD memory card, but you cannot write new files or you cannot edit files on SD memory card,
"Access denied", when SD card is corrupted or broken,

... ...

... ...

you can fix sd memory card errors first and them format you sd card.

Looking at the manual Samsung only guarantee support for cards up to 1GB so I guess your new card won't work in this camera. Perhaps you can take the card & camera to your supplier and try other manufacturer's cards or just lower capacity.