PDF Report sc_pdf_set_y() for image doesn't work

Hello,

I am creating a PDF report with a different amount of lines, depends from report. Now I need to put a picture after all the lines. So far it works, but the picture appears always on the top of the page before lines and not after the lines. So sc_pdf_set_y() is not working for the image. Am I doing something wrong?
$j = sc_pdf_get_y();
sc_pdf_set_y($j+5);
sc_pdf_print($cell_cust_data);

$j = sc_pdf_get_y();
sc_pdf_set_y($j+5);
sc_pdf_print_img($cell_stamp, 40, 0);

BR
Stefan

really no one now how to solve it?