Error:

Glob syntax

# *         Matches any string, including the null string.
# ?         Matches any single character
# [abc]     Matches any one of the enclosed characters
# [^abc]    Matches any one of the characters that are NOT enclosed
# [a-z]     Matches any one of the characters in the range 
# [:class:] Matches any one of the characters in the character class
#           Available classes: alnum  alpha  ascii  blank  cntrl  
#               digit graph lower print punct space upper word xdigit

*.?            # Matches a.b, abc.d 
?.?            # Matches a.b
[abc]*.txt     # Matches atest.txt, does not match dtest.txt
*[:digit:].txt # Matches test9.txt, does not match test.txt

Extended glob syntax

# Enable extended syntax by "shopt -s extglob"
# ?(pattern-list) Matches zero or one occurrence of the given patterns
# *(pattern-list) Matches zero or more occurrences of the given patterns
# +(pattern-list) Matches one or more occurrences of the given patterns
# @(pattern-list) Matches one of the given patterns
# !(pattern-list) Matches anything except one of the given patterns

r?(o)t.tar        # Matches rot.tar, rt.tar. Does not match root.tar
r*(o)t.tar        # Matches root.tar, rot.tar, rt.tar
r+(o)t.tar        # Matches root.tar, rot.tar. Does not match rt.tar
r!(o)t.tar        # Matches root.tar, rt.tar. Does not match rot.tar