Those of you who have read my book know that I steer you away from using the Web Image Optimizer in CorelDRAW. The idea is that it simplifies exporting graphics for use on the Web. The reality is that it makes things much more complicated.
My biggest beef is that there is no easy way to control the size (in pixels) of the graphic it creates. In fact, you can export the same graphic from the same exact file and get bitmaps of two different pixel sizes. This is because the exported size not only looks at the size of the graphic in CorelDRAW but is also dependent on the zoom level.
You are much better off selecting the graphic you wish to export and choosing File | Export. From there you will need to choose between GIF, PNG and JPG depending on the graphic and you will have to enter the exact size in pixels manually. But at least you know what size you are going to get every single time!