why are the emails in my yahoo deleted file being erased on my iphone

I have yahoo email and for the last month, or so, the emails in my deleted file (trash) are erasing on my iphone 3gs, even though the setting for deleted emails to be removed is NEVER. Why is this happening all of a sudden???

Could this be same reason why my calendar is no longer syncing with my yahoo calendar, nor is my phone saving all appointments entered in calendar via my iphone??

Beginning to think this "smartphone" was a waste of money, with as much time I've wasted on it!