reading mail in Thunderbird with Orca in Trusty

[Milton]

Hi all,
I use Ubuntu Trusty with Orca. I notice that reading mails in 
Thunderbird 31.0 with the arrow keys Orca does not find all text. 
Sometimes I then use the letters h, o or p with succes within the 
incoming mail. Pressing f7 gives no result. Any idea? thanks.
Milton