Random black frames in capturing with Intensity shuttle USB3

Hi
Being French ,I am sorry for my poor english.
I am trying to explain the issue . I want to digitalyse VHS videos with Intensity shuttle .

I have digitalysed 9 VHS without any problem and at the 10 th one a lot of random black frames have appeared in the monitor of Media express .

It was impossible to run the capture with a such issue .Afterwards I used a very cheap USB shuttle from an other Brand which worked without any black frame.

Does somebody know this issue ?

Nobody seems to meet this issue . For information I succeed to get a very good result after using a Digital video scaler between the VCR and Intensity shuttle.

If somebody is interrested I will be pleased to give more details in the Forum.