Default External SD card not found

Hi, I've been having problems since flashing a custom rom which is kitkat. When wiping and restoring I get an error along the lines of "android secure file missing" and something to do with am external SD card not being detected even though I've never had one on this phone.
When I try and flash a new Rom, I wipe everything and flash. Everything appears to be successful and then I reboot and it just stays on the boot screen.
Any help would be greatly appreciated.
Thanks

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