I never actually printed from inkscape before since I normally print to PDF first.

I have a very simple page I need to print from inkscape. Le format of the paper is letter and landscape. I checked the measurements in the preference and they are OK.

Now when I try to print, the printer does not recognise the paper I am trying to print to and either I need to set it manually, or either it automatically shrink down the page. I compared the measurements read by the printer and in inkscape and they are the same.

I tried with mm and inch in case there was a conversion problem and it still deos not recognise it correctly. But if I print to PDF and then print the PDF on the printer, it works.

Is this a bug, or there is something I do not do correctly.

It's kind of bug. Sadly Inkscape print capabilities is very poor.

You just have to go into your printer preferences and set any 'custom' settings to the actual paper size, even if the 'custom' measurements are exactly the same as the paper size. EG 'Custom 8.5 x 11' - won't work with my printer, but "Letter 8.5 x 11' will.
The 'bug' is that you have to do this each time you open Inkscape.