From Magento 1.9.2.3 there is a feature called Blocks Permission that allows the defined block can be display in CMS page / CMS static blocks.


If you don't see the Product slider display correctly in CMS page, then look at the System > Permissions > Blocks

If there is no block called productslider/productslider or similar that name, so you have to add it into this grid.


Click on Add new block  > Fill as the following:



then click save.


Now go to frontend and see the changes.


If you have any problem, feel free to create a topic