Card Can Not Be Accessed

Hi, I have a 16GB Extreme IV card. I was able to download my pictures from it into Lightroom, but then when i put it in my Canon 7D camera I get an error message that says Card Can Not Be Accessed. It tells me to reinsert and format. I’ve tried to reformat and gets a about half way through and then this message pops up. I was able to format it in my 40D. I’ve not had this issue with any other SanDisk Cards. I bought the card in July 2010 so its just 7 months old. The 7D is my primary camera so I need to work. Does anyone have any suggestions?



does the card format and work with the 40D? how does it show up and function when connected to the computer? do you have other cards that work normally in the 7D?