FMDB. When closing application, nothing is saved in database

I'm using FMBD framework for working with sqlite database. This is my code for starting work with database:

NSString *docsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
    NSString *dbPath   = [docsPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@",


                                          PTKDatabaseName,
                                                               PTKDatabaseType]];
[[NSFileManager defaultManager] removeItemAtPath:dbPath error:nil];
if (![[NSFileManager defaultManager] fileExistsAtPath:dbPath isDirectory:false]) {
    NSString *bundleDBPath = [[NSBundle mainBundle] pathForResource:PTKDatabaseName ofType:PTKDatabaseType];
    [[NSFileManager defaultManager] copyItemAtPath:bundleDBPath toPath:dbPath error:nil];
}

self.database = [FMDatabase databaseWithPath:dbPath];

And i'm using execiteUpdate for inserting new values into table.

NSString *text      = tweet.text;
    NSNumber *id        = tweet.id;
    NSString *created_at  = [tweet.created_at stringValue];

    NSString *sqlSL = @"INSERT INTO Tweet VALUES (:id, :text, :created_at)";
    NSDictionary *paramethers = @{
                                  @"id"         : id,
                                  @"text"       : text,
                                  @"created_at" : created_at};
    [self.database executeUpdate:sqlSL withParameterDictionary:paramethers];

All works perfectly, values exist in tables and i can get them.

But when i'm fully closing application and there opening agin, my database is empty. What am I doing wrong?