I have a perfectly nice drawing on my screen. It is made of 3 squares on top of each other. The bottom one is brown, the middle one is black, and the top one is brown showing a black letter.
The image was imported from a PDF file created with PDFcreator.

When printing the image I get a black square.
When printing on a virtual PDF printer (linux) I get a black square.
When I save my image as a PDF file, the file show a black square.

When I open the svg file with FireFox I get the right image (a black letter in a brown square)
When I print the image from Firefox with the PDF plugging, I get a black square.

At this point things are consistent, I cannot print the image, but it shows on the screen.

However if I print the file from Firefox with the virtual PDF printer, I get the rigth image (with a lower quality, but it shows).
Same if I print from Firefox on a physical printer.I get the right image.

Since I'm a newbie with Inkscape I wonder what I screwup by ignorance. But since I'm ignorant I cannot find the right
direction to find the right answer, right?
Any idea where to begin ?

It may be that the drawing uses a feature that doesn't convert well to another format. But to know for sure you'll need to post the file for us to examine.

Thank you for your reply.
I guess I can post the file using svg marks and uploading the file to petaimg.com.

Ok, so the problem is that the drawing uses masks and (correct me if I'm wrong) masks don't convert properly to other formats.

The mask is actually a bitmap image... so your drawing isn't a true vector. You can examine the structure by selecting an object and at the bottom of the Inkscape window it'll tell you you have a group selected. So you ungroup it and select the next object. Repeat the process until there are no more groups. Eventually you find that one is a mask and you can release that to see the bitmap.

I had a look at the file with a text editor and found the mask.It seems to me it written as a png file .

Here is how the bit map is defined, I guess:
<mask
id="mask37"><image
xlink:href="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEAAAABACAAAAACPAi4CAAAAAXNCSVQI5gpbmQAAAQFJREFUWIXt1cEOgzAMA9Bm///P7DIgTWw3LQc0qRzQpNWvISuZHe3Z9XmY38AGXgLsIWBRmAQs1TAHWGut9e/vFADyUwDKjwCLn9P80YDvOc5rwPec5CVg8Y7mpwD83jQvgDtjIt+MjfUzc3WRLGQVXHueObYRAVzN/l4G/DP736IK5DwXEJDyhxAAAPJCyADcnwsJwPVzIQFuJbEGwC2U8qiJ4PzPvgvx/Is8Pkjh/Ks8Ocrd+Zd59S6MZpEAarOIA8VZ9Fucv6zOIlZBeRYRoD6LMNA9s6+jCISeHcN8aOKw54MKFvIdsJL3wFLeA5WeS6DS83zRP9eVCjawgT8GvtqBUHrJ/PuoAAAAAElFTkSuQmCC"
width="1"
height="1"
id="image39" /></mask>
.....etc

And here the bit map is called by url and positioned on the page:

id="g35"><rect
width="1"
height="1"
x="0"
y="0"
transform="matrix(1,0,0,-1,0,1)"
mask="url(#mask37)"
id="rect41"
style="fill:#f3bf94;fill-opacity:1;fill-rule:nonzero" /></g></g></g></svg>

So, ok its a bitmap image (the top square). But it is placed as a vector in some way. Right?
That's probably why it shows on the screen (?)

You explain very well, that "masks don't convert properly to other formats". And I suppose your are right, since vectorizing a bit map is not so easy.
Now without knowing the ins and outs of inkscape, I guess it is when the file is send to the printer, that inkscape does not interpret the bit map.(tell me if I am a complete idiot, it won't hurt me!). Could it be considered as a flaw ? I mean, since inkscape keeps the bit map information in its native svg file format, the printing of the file by inkscape should show the bit map. Logical no? At least for me.
Isn't that an issue that should be addressed by the developers, which by the way I thank for the wonderful work they are doing ?
(May be it is not the right place to debate this issue,sorry)

I say that, because I am very frustrated, since it looks like a dead end for me. I really want to rewrite (=save) the image in a PDF format and keep the image as it looks on the screen.
I looked within inkscape, and I did not found a way to vectorized directly the mask.Manually it is feasible, but let say you have a few hundred of masks of different sorts. Fastidious!
Do you know of an open-source-way of converting the svg file to PDF and keeping the bit map information?

Again, thank you MicroUgly, for the interest you are showing, regarding my tiny drawing.

My experience with this sort of stuff is kinda limited. Much of my understanding is based on assumptions--so I won't take guesses at the problem, because it won't lead to a solution anyway

If your image was created using PDFCreator, what was the image before that?

The image came from a cross stitching software. The image is saved under some obscure file format with extension wxs. That's why I found a way to convert the image wxs -> pdf with PDF Creator.Then I'm able to import pdf with inkscape and most of the image is in vector form.
Anyway I'm not sure my problem is of any interest for the Inkscape community, unless my problem can trigger an improvement of Inkscape in some way.
What do you think MicroUgly ?
I am going to have a look at PDF Editor see what I can get some results.

Unfortunately I really don't know this stuff well enough to make suggetions. I'm surprised PDFCreator uses masks in the PDF it produces. Whilst cross-stitching might be rare here, having to print a document that uses a bitmap mask wouldn't be. I'll try to remember to examine this issue later today.