Creasing a black patch printed and laminated coated card

[mulo_g]

I have to perfect bind a book. Cover is coated card 250 gsm printed solid black (on 4 color). Cover has to be pp laminated on top. When Side creases are done, white ugly line appears where it is creased. Spine creases are ok. I have tried reversing the crease/groove. What can be the solution?

 

[pippip]

To late if its printed but changing the paper grain might help?