As I understand, it is a grain focuser. When you just starting using a grain focuser, it is not that clear what to look for and where the grains are. It's getting better with experience. Don’t look for the image, you will not be seeing it. Concentrate just on the grains. Locate the grain focuser in the area of the image with maximum density, close the lens aperture a few stops, and try to look through the focuser on the separate grains. Move slightly the enlarger focusing mechanism, and you will see that the grains became more or less sharp in the focuser. And it is no difference how sharp the image by itself. The negative theoretically is the flat surface located parallel to the focusing board, that means that all grains are on the same distance to the focusing board, and all of them will be visible sharp when enlarger focused correctly even if the negative not sharp at all.