fix return for single checkbox

Hi, 
It's my first pull request on github so I don't know if I did it perfectly. 
And I'm french so sorry for my english :)

To carry on my issue about the checkbox, I think if we are in the first "if" (means the single dimension array) we should return only the value for the checkbox because if there are many of them, that should go on the second "if" ( the multi dimensional array) and works perfcetly.

What do you think?