Sometimes it can happen that you've followed all the installation and configuration steps, but the gallery fails to load the images and all you see is a black box where your images should be.
99% of the time this is because of a conflict with another plugin due to the other plugin using a javascript framework, such as Prototype or JQuery, which conflicts with Mootools, which is the javascript framework used for the SmoothGallery. Unfortunately if this is the case there is very little that can be done other than search for an alternative plugin which uses a non-conflicting javascript.
Through my own testing, together with useful feedback from Dynamic Content Gallery users, the following plugins have been identified as causing Known Conflicts with the Dynamic Content Gallery. Where a non-conflicting alternative has been identified, it is also mentioned below. This is not an exhaustive list and will be added to as and when conflicts are identified.
Lightbox 2 alternative use shadowbox
Twitter Tools 1.5b2 upgrade to Twitter Tools version 1.5b3
Formbuilder alternative use CFormsII