Make sure that your files are in the correct directory because if they are wrong on the path DGDK will not let you know this, it will just fail to correctly display the image. Most people try to put their content in the project\debug folder. It does not go in the debug folder by default. You can set the project to use this as the working directory but by default the project uses the directory above Debug for the initial working directory. Also, you do not need a game loop to draw the image. You should, however, use the dbSync command like so:
dbSyncOn ();
dbLoadImage ("image.jpg", 10);
dbPasteImage (10, 1, 1);
dbSync ();
dbWaitKey ();
If the image is in the correct working directory this code will display the image at the given location. Most often in my experience it is a path issue.