Help-cant see email history whenever reply, all and forwarding

Whenever reply, reply all and forward, the previous email is gone. I have checked the preference and everything is fine. Can someone help on this..much appreciate

mid 2011 MacBook Air, 64 Gigs, 2 gigs RAM

Ensure there is nothing selected, or that you have selected the portion you wish to reply to, before clicking Reply,...

Thank you, but nothing is selected, i found out problem occur when i reply, reply all and forward incoming email in rich format. I dont have problem in reply, reply all and forward email in plain text