IWR1642BOOST: Cannot Flash Due To "Invalid Files"

I'm using UniFlash to try and flash two images onto my IWR1642BOOST. The two images were downloaded and installed by the SDK package and I am following this tutorial step by step(currently on pg. 19). When I try to flash the images that it mentions, UniFlash reports error after checking the image headers saying "xxxxx file indicates it is not a valid file to flash to IWR1642", but this is exactly the file that the tutorial had asked me to flash onto the IWR1642? I have made sure the COM port is correct and power cycled the device multiple times. Please help, thanks a lot!