Weird problem with URSA 12K and Angelbird CF cards

Hello, I have a strange problem with CF cards and Ursa. A few weeks ago I put one card in the slot, it turned out that the camera did not see it, then I put it in the reader, the reader did not see it either. I have reported the problem to Angelbird. Before sending, I checked again. Suddenly, it works! I say ok. Today, I put in a second card and it worked fine yesterday. It turned out that Ursa cannot see her .... I put it in the reader, the reader worked, the card is visible in the windows. Then I put it in Ursa and it works, all right. Has anyone had a similar problem?

My software is 7.7

Maybe this cards have a problem..., do you know better cards than Angelbird which i can buy in Europe?