PDF export in wrong size ?!?

[TomCarpenter]

(Sorry for the English!/Google Translate)
I would like to create a book cover.
According to Lulu (the online printer service), the PDF must be created like this:
File Type: PDF
Page Count: 1
Dimensions: 16.79 x 11.94in / 426.47mm x 303.28mm
Spine Width: 0in / 0mm
Fonts: Embedded
Layers: Flattened

When I open the PixelmatorPro document I enter: 426.47mm x 303.28mm

I export to PDF, upload to the print service Lulu and get the message:

“Incorrect PDF Dimensions: The dimensions of your PDF are 1776.94” x 1263.65” (69.958mm x 49.750mm).

Whats wrong?

[Tony_1993]

Same problem here, A4 format in my case