New memory card i bought not working on camera.

[leito721]

I bought a 64GB SanDisk Ultra 48MB/s SDXC10 and T1i says card cannot be accessed. Reinsert/change the card or format card with camera

 - I tried to go to the settings then format and it says "Cannot Format" Change card.

[Waddizzle]

Aside from having a bad card, there are two possibilities.  One, the "write protect" tab is in the "protected" position.  Two, the capacity of the memory card is too high for the camera to handle.

The Instruction Manual does not give recommended card specifications, curiously enough.  Other Rebel cameras state that cards should have a capacity of 32 GB, or less.  The cameras simply do not have the smarts to know how to perform a low level format on cards over a given size. 

You could try using your computer to peform a low level format on the card.  The card would need a FAT32 format, which is the default used by MS Windows on the most recent OS versions.  Now you need to perform a format in the camera to define the folder structure.  You do this by selecting format, but leaving the "low level format" box unchecked.

[jrhoffman75]

A 64GB card would be SDXC type. 

I suspect the T1i is only SDHC compatible, which would be 32GB max. 

[ebiggs1]

"I bought a 64GB SanDisk Ultra 48MB/s SDXC10 ..."

SDXC format is NOT backwards compatible with devices that only take SD (128MB to 2GB) or SDHC (4GB to 32GB) cards.   It won't fly Oriville. 

[RobertTheFat]

I don't doubt that John and Ernie have hit the nail on the head. But before you give up and return the card, you might want to at least make sure that your T1i's firmware is at the latest rev level. Maybe you'll get lucky.