Boot into Windows 8.1 and 7 problems

I have Windows 7 (64 bit) on a SSD. I just installed Windows 8.1 (64 bit) on a HD. I installed Easy BCD. Windows 7 works fine. When I choose Windows 8.1 I get a "digital signature" error. I tried repairing the disk as it said but nothing works.
What do I do???