Form Error Message in English but should be Spanish

https://www.dropbox.com/s/wg3hqhy5y9yh3o7/Screenshot%202014-08-01%2023.35.35.png

See the image above.

This is for form: http://form.jotformpro.com/form/41971422765964?

To replicate this just try to press 'siguiente' before completing the form.

I know I can edit the error messages in the language section but this particular error message is not listed there.

How do I change it? 

Hi,

I cloned your form to test it and I did indeed find that error in the list of errors you can edit.  You can find it here:

Please let us know if you have any further questions and we will be happy to help.

Thank you for using Jotform!