Hi Lizzie, difficult to know what might be causing your hood to not latch properly.  The mechanical latch system is identical between the S and non-S, so that shouldn't be an issue.  

If someone replaced the hood, perhaps there is an alignment issue??  If the hood was replaced due to an accident, the alignment would be suspect.   

Here is the link to all the parts for the hood latch.

Good luck!
Ken

have a 2010 mini base put a s hood on hood will not latch  need help