Since none of us have any idea what card or camera you're playing with please give specifics.
CARD BRAND & EXACTLY what version, class, size & anything else that may narrow down exactly what it's performance specs are.
There are so many new card types these days which were developed after the camera people have & they are therefore not accepted by the camera.
Are both cards the same? Have you used them before or are they new? From what I can see when searching for a 16 gig Sony card I can ONLY find cards meeting the new UHS class & I don't think your camera can recognize that card style. My downloaded manual for the T4i lists it as needing SDHC class 6 or higher BUT it couldn't know about newer styles of cards that would be developed later than at the time the camera was built & the manual wrote. It's a very hard topic to nail down specifics for camera / card compatibility.
I suggest you may try different brand of SD card . The SD card could be defective. You may try SanDisk Extreme Pro SDHC's If that does work for you. Although i had few SD cards in the past gave me issues with the Lock slider locking on me while inserting the SD card into the camera. Other thing to consider the camera firmware may not recognize the SD card... You may watch this Youtube Video I hope it helps