Kodak 7590 New SD card will not format

Format it on a PC, and try again.

The DX7440 works with MMC and SD cards, which max out at 2GB. While your 4GB SDHC card fits into the slot, it is electronically incompatible and will not work with this camera. You need to stay with SD cards, 2GB and smaller.

The Z740 works with MMC and SD cards. Your 4GB card is actually an SDHC card. While it fits into the slot, it is electronically incompatible and will not work. You need to use MMC and/or SD cards, 2GB and smaller.

First check make sure the SDHC card is unlocked I'll provide a diagram for that also I just checked your camera's memory capacity and it's only good for a 1 gig SD card which if using an SDHC memory card might go to 1.5 stretch to 2gig maybe but not a 4gig. My first impression is you got to much memory card for the camera. You might be able to go to the Kodak site and download updated firmware to allow the camera to function with the larger card but that's a maybe as well.
Here are the diagrams



And the memory capacity chart for your camera

as a short cut try putting the sd card into your sd slot and format it with your computer

Your card might be protected.
Please change the position of the lever on the SD card.

Your camera is only supporting SD/MMC Cards (up to 2 GB)

The card that you currently have might be faulty. Please try another card.
You might also need to switch the camera over to saving pictures directly onto the SD card.1: Menu, Cam settings, Chose AUTO or SD card option Press OK
Note: If the SD card isn't in the camera or is unreadable the camera will automatically go back to saving you taken pictures on the internal memory.

The Z740 supports only MultiMediaCards & SD Memory Cards. 4GB and larger SD cards are usually SDHC (Secure Digital High Capacity) types - and bear the SDHC mark on the label. These cards are not compatible with this camera. Use only MMC and SD cards. SD cards are 2 GB and under - although *some* 4 GB cards are marked as SD too; these cards may or may not work. If you purchase a 4 GB SD (not SDHC) card, make sure that it can be returned if it doesn't work reliably in your camera.

try to format using a card reader through PC...

I guess you put the SD adapter into the card reader right out of the box? You first may have to partition/format it after unpacking it. Under WinXP I can recommend an utility "DiskPart" which you can start from the command prompt (Run... -> cmd). For further instructions (if it sounds to you to be the problem ) contact me again.