Unable to upload txt file when creating new message

Hi Expert,

We installed SolMan 7.1, but we are not able to upload txt file when
create a new message, detailed steps as below:

• 1. Click on “New
    Message” under “Common Tasks” in the left side
• 2. Click on
    “Attachment” under “Create Message”
• 3. Click on “Add”
    under “Attachment”
• 4. Select file and
    click on “OK”
• 5. But as the result, it says “No attachments. Select Add to
    upload a new attachment.”

Could you please help advise the reason and solution?

BR

Takashi