FortiWiFi 50G-5G firmware upgrade 7.0.17 to 7.4.9 issue

I have a Fortigate FortiWiFi 50G-5G  device. As per upgradation path in forticare it's showing the 7.0.17>7.4.9. But when i upload the file to fabric management to upgrade the firmwire,its showing file not match the device. I've downloaded the correct file. Can anyone help me?