Language switcher doesn't appear I have enabled the "locale" and "content translation" modules. Also I have two languages in my Drupal, Spanish and English, after that I have configured the detention method by URL. 

I have finished my English page and I just need to translate the website to Spanish. When I set the language switcher to the website (the header or a columns) of my Structure I don't see anything. I can click on "translate" button of the blocks of my web, I see the "spanish" option, I click in "translate", but I get this message: 


  This string uses the Full HTML text format. Strings with this format
  are not allowed for translation.


Ok, I change the format to Plain Text but I lost my HTML format, styles... I can't translate and I can't see the switcher to change to Spanish or English. 

Drupal version 7.4.
To translate custom block text you need to do the following:


Download the Internationalisation module (i18n)
Enable String translation module (i18n_string)
Go to Configuration > Regional &amp; Language > Multilingual Settings >
Strings (admin/config/regional/i18n/strings)
Enable Full HTML in Translatable text formats
Save