mercurial - What could cause thg and hg to give different results for diff

Question

I have a changeset and if I do

 hg diff filename -r rev1 -r rev2

I get a diff output for the changes for that file if i do

 thg -vdiff filename -r rev1 -r rev2

I get a message box that says "There are no file changes to view"

What could cause them to disagree?

Edit in response to comment, here is a genericized version of what the first diff outputs

 diff -r rev1 -r rev2 path_to_file
 --- a/path_to_file       DateTime
 +++ b/path_to_file       DateTime
 @@ -52,13 +52,13 @@
                  {
                      // Comment
                      // Comment
 -                    OldCode
 +                    NewCode
                  }
              }
              catch (Exception ex)
              {
 -                OldCode
 -                OldCode
 +                NewCode
 +                NewCode
                  RefCode
                  RefCode
              }

Answer 1

Your usage is wrong, although that's not immediately apparent when you're viewing the results.

Try this:

thg vdiff -r rev1 -r rev2 filename

Note that the filename is now at the end of the command