By default a PDF doesn’t have any preview. When a PDF is uploaded to Scene7 and you select the option “Rasterize," preview images are generated that imparts the preview to the PDF. However, when you delete those rasterized images, the PDF reverts to the default PDF icon. (This reversal can take some time as those rasterized images could still be there in the Trash.)
Scene7 uses the composite image of a .psd file when displaying in SPS. If this message appears, it means that the composite image was not included in the original .psd file.
You can run into this issue when saving a layered .psd file, and uploading it into SPS without maintaining layers.
To fix the error, open the .psd file in Photoshop and resave it using the Maximize Compatibility option. When saving the document, you are prompted with a Photoshop Format Options dialog box with the option to Maximize Compatibility. Make sure that the box next to Maximize Compatibility is selected, and click OK.
If you don't receive the dialog box that allows you to select Maximize Compatibility, turn on the option. On Mac OS X, go to the Photoshop menu and then select Preferences and File Handling. Then, select Ask in the pop-up menu next to Maximized PSD File Compatibility. On Windows, open the Edit menu and navigate to Preferences and then File Handling. In the dialog box, select Ask in the pop-up menu next to Maximized PSD File Compatibility.
Once you've saved the .psd file using the Maximize Compatibility option, you can open the new file and see a thumbnail without error.