I want to display image in report column. My table has composite primary key: ID and DATE. When I add these columns in BLOB attributes as Primary Key Column 1 and Primary Key Column 2 report can not find data because of DATE column. Is it a problem in date format, or something else?
I'd suggest you to use only one column as a primary key column (a sequence or - if your database version supports it - an identity column).
Combination of [ID, DATE] you currently have can then be set to unique key (set both columns NOT NULL to "mimic" what primary key would do).
Why? Although your data model probably is just fine, certain Apex functionalities "suffer" from such things and prefer having a single-column primary keys.