Printing HardCopy of Report – Alternate Line Shading Trouble

My report looks great in both Print Preview and when creating PDF.
However, when I print hardcopy from within program, the alternate line shading on shaded lines only goes 1/2 way across page.

If I print from the PDF it’s correct and goes full width of page.
code for Detail.OnPrint is standard code as shown below…

' — style script start
detail.BackColor = iif(_styleCtr mod 2 = 0, rgb(255,255,255),rgb(240,240,240))
_styleCtr = _styleCtr + 1
' — style script end

Also, same report has a subreport in footer and alternate highlighted lines in subreport print hard copy correctly.

I’m puzzled by this – any suggestions as to where to look??