Why is $1 empty in my substitution?

while(<TOCFILE>)
{
    $toc_line = $_;
    $toc_line =~ s/<inlineFig.*?(../pics/ch09_inline99_*?.jpg)*?</inlineFig>/<img src="${1}" alt="" />/g;
    $new_toc_file .= $toc_line;
}

<img src="../pics/ch09_inline99_00" alt="" />

<img src="" alt="" />

inline99_*?.jpg
        ^^^

($PATTERN)*?

$_ = 'one two three';
s/(w+s*)*/$1/;
print;

while(<TOCFILE>)
{
    $toc_line = $_;
    $toc_line =~
      s/                  # replace the follwoing

         <inlineFig                     # match this text
         .*?                            # then any characters until the next sequence matches
         (                              # throw the match into $1
            ../pics/ch09_inline99_  # ..picscho9_inline99_
            d*?.jpg                   # folowed by 0 or more numbers
         )*?                            # keeping doing that until the next sequence matches
         </inlineFig>                  # match this text

       /                  # with the follwoing


         <img src="${1}" alt="" />    # some text and the result of $1 above.

       /xg;  # <- the x makes it ignore whitespace and #comments
    $new_toc_file .= $toc_line;
}

#!/usr/bin/perl

use warnings;
use strict;

my $new_toc_file;

{
    # localizing $_ protects any existing value in the global $_
    # you should localize $_ even if you choose to assign it to a variable

    local $_;

    while(<DATA>) {
        # in the absence of the bind operator =~, s/// operates against $_
        s!<inlineFig.*?(../pics/ch09_inline99_.*?.jpg)</inlineFig>!<img src="$1" alt="" />!g;
        $new_toc_file .= $_;
    }
}

print $new_toc_file, "n";

__END__
<inlineFig>../pics/ch09_inline99_00.jpg</inlineFig>