Dell Precision Tower 5810 OpenCore can't install Big Sur

I successful install Catalina with OpenCore, but is impossible use the same EFI for Big Sur.
I try different EFI's but every time show mew the same error that i show in the uploaded image.
Please , someone help me

I am using the last OpenCore 0.6.7
Boots, install and work perfectly with Catalina but not with Big Sur

Author: PepeCortizona