Custom module .install does not create table in database I want to create database table for my custom module.

Inside mymodule.install I have:

function mymodule_schema(){
    $schema['a_visits'] = array(

    'description' =&gt; 'visits table',
    'fields' =&gt; array(
        'id' =&gt; array(
            'description' =&gt; 'make id primary key auto increment',
            'type' =&gt; 'serial',
            'not null' =&gt; TRUE,
        ),
        'oferta' =&gt; array(
            'description' =&gt; 'nazwa oferty',
            'type' =&gt; 'varchar',
            'length' =&gt; '255',
            'not null' =&gt; TRUE,
        )
    ),
    'primary key' =&gt; array('id'),
    );
    return $schema;
}

function mymodule_install() {
   drupal_install_schema('a_visits');
}


function mymodule_uninstall() {
   drupal_uninstall_schema('a_visits');
}


Then I've moved the module's file to server under sites/all/modules/custom/mymodule and enabled it via admin panel. Unfortunately no table in database has been created (the module is listed as active now).
hook_schema alone is sufficient to create database tables. I assume you are just disabling and then enabling the module which will not help you to create tables in the database.
To get it working, admin/modules' locate your module and disable it. Then navigate to 'admin/modules/uninstall' and again locate your module and uninstall it. 
After this, go toadmin/modules', and enable your module.
Now you can find the respective tables in your database.

You can also use drush for the same.
drush dis module_name, then
drush pm-uninstall module_name and finally
drush en module_name.

Also, as per @OPTASY Canada, do check your dblog for any warning or error.