Driving a 12 pins LED display

Hi There,

First post on this forum, any idea would help.

I have an controller board with two 74HC595 shift registers serial connected and a 12 pins 8 segments cathode LED display. My board is complete now and the multiplexing segments work (4 positioning, 8 for segments).

But, something is wrong. If I set the position to high then it does not show the number, if I set it to low, it shows the number. That feels like a little glitch. Still okay.
But the pain is that I can show only one kind...

Driving a 12 pins LED display