One important thing that is missing in the description of your issue is the version of Access that you are using, and the format of your Access front-end database. Since you are trying to use the Attachment Control, I presume it is 2007 or later. But that control is designed to use the Attachment data type - see this thread where some of the issues are explored.

The attachment data type simply stores a link to one or more files stored somewhere outside of the .accdb format front-end. If you want to actually store the image in SQL Server, then you want to choose one of the SQL Server data types that can store the image and use either the Image control or one of the other options.