Pentax *ist DS

Hi all, I have been given a Pentax *ist DS SLR that uses compact flash. This is not my normal models I use, I have two K20s and K10 as backup. I have a problem with the *ist DS camera, all functions, modes, autofocus, flash, etc work. But when a picture is taken no image is saved to the card. I have used several cards all with the same result. I have used the cards in other cameras with no problems recording images. The cards are 512mb. Pictures taken on other cameras can be viewed on the Pentax *ist DS. but any taken using the Pentax *ist DS are no saved. Has anyone experienced similar with one of these models, what was the problem and was it fixed. It would be a shame to discard the camera as it looks for all intents and purposes as brand new. Any ideas or advice. Thanks, Steve

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