Hello,
The guys at sb wrote the drivers for the Atik range, I believe they are listed as Atik universal. We normally use the ASCOM drivers. The "preview" or "pre" function alters where precharge is subtracted, either on the camera or on the PC. This normally need to be left un ticked and only ticked for some of the smaller CCD cameras when image download speed is a priority over image quality . If this box is ticked when taking long exposures there will be problems with the downloaded images. Do you have this ticked?
Best regards
Vince