slim - Empty variable output using Twig -

i have slim/paris/twig application , have strange problem output.

this code:

the title: {{ share.title }}  

the output nothing.

but if use:

the title {{ share.title | lower }} 

the output is:

the title first title

{{ share.title | raw }} works too, don't want use because shows accented characteres weird characters.

any idea how solve ?

thanks