Widget visible problem

Hi, i have a little widget problem with the dropdown selection with image.
I insert the widget on my header but when i click the dropdown, the menu is like under the other elements.
See this screenshot:

http://www.alexdex.com/error.jpg

How can i solve it?

Thank you and sorry for my english

http://wordpress.org/extend/plugins/transposh-translation-filter-for-wordpress/