Gordon, if you have refilled the cartridges yourself, there is probably a sensor in the cartridges that has to be reset. Some manufacturers go to great lengths to prevent this as it reduces their revenue - they rely on ongoing ink sales - but there is always someone who can find a way around it.
If the cartridges are fresh ones, you have a service problem.
Perhaps you can download repair manuals from their site.
Munro, May 2011