Inbox messages

I can't seem to be able to open my email replies. When I get the reply, it shows who has sent it and the first few words from the response but then when I touch to open it, all that comes up is the email that I sent in the first place? ?This is really frustrating me. However, if I then email the given person again I can then see the email he /she sent me as its then listed as a conversation. can I sort it out so I can just press the email and read the new reply? ? If anyone else has had this problem and have then found the answer could you please share. ..