Ikea Billy shelf connecting screws length wanted

Hello,
I have just bought connector screws for my Billys from the Ikea service afterwards. At home, I find that the screws - with the corresponding sleeves - in my opinion are much too short. When I join both parts so that they hold with a slight turn, they are only 2.5 cm wide, but the two side parts of Billy that I want to connect are much wider. Did they give me the wrong ones at IKEA or am I thinking wrongly? Before I go to Ikea again - 2 hours effort - who knows about this?

Best regards
christel123

The sleeve nut is probably too short or the screw. The gentleman from IKEA probably reached into the wrong drawer.