Are some fibre-tip pens invisible to scanners?

[Murphyv310]

Lots of problems scanning or copying some shades of blue especially for some reason. I find it hard to print £5 and £20 notes! Would be nice if I had one to copy some days.

Hi.
Sam you must have a scanner that isn't up to the mark.
the £20 notes I scan come out fine and the shops take them fine even though nothing is on the back