The fittings on intex pools are not the same size as on a regular pool as you have discovered. If you have the "small" intex skimmer, then you can buy an intex branded adatper that is used to connect a regular vacuum hose. If not, you'll have to make or find some kind of special adapter.

This guy used a $3 part from ace hardware to make such an adapter for this very purpose:
https://www.youtube.com/watch?v=YfLnsQnt5mc

Here's an adapter similar to what this guy is suggesting - except from amazon instead of ace hardware: http://www.amazon.com/Pool-Tools-80-...8ZXDH4SP7BH6K2