Dell latitude E-6420

I have benn using Dell Latitued copmputers for many years.  Mostly the E6400

I have been using a Dell Latitude E-6420 for a few months.  I just puchased a new larger hard Drive for it.  

The Hard Drive Boots with UEIF, same as my old Hard Drive.  The new Hard Drive uses Windows 10.

When I tried to Boot using the New HD.  I got no bootable  device found.  I checked the boot sequence and  it

was set for Windows Boot Manager, UEIF, RAID OFF.  I changed to Legacy, but It still will not  Boot.  It said said trying to boot from Legacy, but no other info.  Im no expert, but I think it should boot from  UEIF or Legacy???  Any advice.???

Harry