Hello
To connect your page => Edit your ES page => in the meta box Language (on the top right) choose in the autocomplete input field the existing EN page as translation and update.
What happens? Is it OK?
If not could you try with :
your theme + only Polylang:
=> if it works add your other plugin one by one to find the conflict.
=> if it doesn't work try with a default WordPress theme like Twenty twelve and just Polylang.
And tell me what you get.