new fields in contact form prestashop 1.6

[slykereven]

Hello,

 

I searched for a few days how to get new fields in the contact form with the integration of a variable in the email sent to the customer. 

I followed this tutorial

http://nemops.com/adding-new-fields-to-prestashop-contact-form/#.U9CxH_l_tvD

but {my_variable} sent in the email is blank. 

 

If anyone knows a way, thank you in advance