exclude error "cannot match" but dir exists

[RL]

The source:

rufus@Air-PC:~/WK/testin> dir
total 628
-rw-r--r-- 1 rufus users     67 Feb 16 17:24 aud-link.txt
-rw-r--r-- 1 rufus users   3759 May  3 23:39 bad-world_rant.txt
-rw-r--r-- 1 rufus users   3981 Feb  9 13:00 bernie-rant.txt
-rw-r--r-- 1 rufus users 584635 Feb  3 16:13 bldg_bath_fans_FineHomeBuilding.pdf
drwxr-xr-x 3 rufus users   4096 Apr 17 17:01 dir1
drwxr-xr-x 2 rufus users   4096 May 11 08:03 dir2
drwxr-xr-x 6 rufus users   4096 May 12 17:07 dir3
drwxr-xr-x 2 rufus users   4096 May 12 08:16 dir4
-rw-r--r-- 1 rufus users      2 May 13 07:56 dummy
drwxr-xr-x 4 rufus users   4096 May 12 17:47 fldr-m-tst
-rw-r--r-- 1 rufus users      2 May 12 17:37 m
-rw-r--r-- 1 rufus users      2 May 12 17:18 m-tst.txt
-rw-r--r-- 1 rufus users      2 May 12 17:19 tst.m
-rw-r--r-- 1 rufus users      2 May 12 17:18 tst-m.txt
drwxr-xr-x 3 rufus users   4096 May 12 17:57 zfldr
rufus@Air-PC:~/WK/testin>

The commands that fail: (slight variations of wildcards and quotes and a 
relative path. The first example is the cleanest and simplest. The last example 
is using ** and it also fails.)

rufus@Air-PC:~/WK> rdiff-backup -v3   --include /home/rufus/WK/testin/dummy 
--exclude /rufus/home/WK/testin/dir3   /home/rufus/WK/testin    
/home/rufus/WK/testout2
Found interrupted initial backup. Removing...
Fatal Error: Fatal Error: The file specification
    'b'/rufus/home/WK/testin/dir3''
cannot match any files in the base directory
    'b'/home/rufus/WK/testin''
Useful file specifications begin with the base directory or some
pattern (such as '**') which matches the base directory.

rufus@Air-PC:~/WK> rdiff-backup -v3   --include /home/rufus/WK/testin/dummy 
--exclude dir3   /home/rufus/WK/testin    /home/rufus/WK/testout2
Found interrupted initial backup. Removing...
Fatal Error: Fatal Error: The file specification
    'b'dir3''
cannot match any files in the base directory
    'b'/home/rufus/WK/testin''
Useful file specifications begin with the base directory or some
pattern (such as '**') which matches the base directory.

rufus@Air-PC:~/WK/testin> rdiff-backup -v3   --include 
/home/rufus/WK/testin/dummy --exclude /rufus/home/WK/testin/dir3?   
/home/rufus/WK/testin    /home/rufus/WK/testout2
Found interrupted initial backup. Removing...
Fatal Error: Fatal Error: The file specification
    'b'/rufus/home/WK/testin/dir3?''
cannot match any files in the base directory
    'b'/home/rufus/WK/testin''
Useful file specifications begin with the base directory or some
pattern (such as '**') which matches the base directory.
rufus@Air-PC:~/WK/testin>

rufus@Air-PC:~/WK/testin> rdiff-backup -v3   --include 
/home/rufus/WK/testin/dummy --exclude /rufus/home/WK/testin/?dir3   
/home/rufus/WK/testin    /home/rufus/WK/testout2
Found interrupted initial backup. Removing...
Fatal Error: Fatal Error: The file specification
    'b'/rufus/home/WK/testin/?dir3''
cannot match any files in the base directory
    'b'/home/rufus/WK/testin''
Useful file specifications begin with the base directory or some
pattern (such as '**') which matches the base directory.
rufus@Air-PC:~/WK/testin>

rufus@Air-PC:~/WK/testin> rdiff-backup -v3   --include 
/home/rufus/WK/testin/dummy --exclude '/rufus/home/WK/testin/*dir3'   
/home/rufus/WK/testin    /home/rufus/WK/testout2
Found interrupted initial backup. Removing...
Fatal Error: Fatal Error: The file specification
    'b'/rufus/home/WK/testin/*dir3''
cannot match any files in the base directory
    'b'/home/rufus/WK/testin''
Useful file specifications begin with the base directory or some
pattern (such as '**') which matches the base directory.
rufus@Air-PC:~/WK/testin>

rufus@Air-PC:~/WK/testin> rdiff-backup -v3   --include 
/home/rufus/WK/testin/dummy --exclude **   /home/rufus/WK/testin    
/home/rufus/WK/testout2
Fatal Error: Switches missing or wrong number of arguments
See the rdiff-backup manual page for more information.
rufus@Air-PC:~/WK/testin>


This makes no sense. The file "dummy" and the directory "dir3" exist in the 
base, but rdiff says "...dir3...cannot match". How is this possible?

And how is "--exclude **" (last example fail) wrong? Switches? Arguments?


Thanks for any help.
Rufus