Dark Grey U or Cream U? Help needed!

[vidasmile]

Hello, I am a beginner hobby breeder. 4 months earlier we had our first litter. One hamster is very interesting for me. I guess he is Dark grey Umbrous (dgdg U-) or Cream Umbrous (ee U-). I just can not understand how can he be umbrous if his mother is Golden banded and father is black banded (umbrous gene is dominant).
I put the photos of a hamster and the litter.