sqlite3_step return unknown error on iPhone

Question

I try to use sqlite on iPhone. But I have the following problem:

NSData * image = [[NSData alloc]initWithContentsOfURL:[NSURL URLWithString:image_url]];
    NSString * query = @"INSERT INTO PHOTOS( image_url, image ) VALUES (?, ?)";
    NSInteger result = -1;

    sqlite3_stmt * pStm;
    do {
        if (sqlite3_prepare_v2(database, [query UTF8String], -1, &pStm, NULL) == SQLITE_OK) {
            sqlite3_bind_text(pStm, 1, [image_url UTF8String], -1, SQLITE_STATIC);
            int err = sqlite3_bind_blob(pStm, 2, [image bytes], [image length], NULL);
            if (sqlite3_step(pStm) != SQLITE_ROW) {
                NSString * strerr = [NSString stringWithCString:sqlite3_errmsg(database)];
                NSLog(@"%@", strerr);
            }
            else {
                result = sqlite3_column_int(pStm, 1);
            }

        }
        else {
            NSAssert(0, @"Error while prepare");
        }           
    } while (sqlite3_finalize(pStm) == SQLITE_SCHEMA);

When executed, this code function sqlite3_step returns an error SQLITE_ERROR with description "Unknown error" . Did anybody have same problem and maybe somebody solved it?