What am I doing wrong?

You are not showing the full script. See SSCCE.

Here's one showing how it works:

$ cat show.cgi 
#!/usr/bin/perl
use strict;
use warnings;
use CGI;

my $store = CGI->new;
my $cell = $store->param ('cell');
my $td = $store->param ('target_dir');

print $store->header (-type => 'text/plain'), 
    "Cell is $cell and Target Dir is $td\n";
$ ./show.cgi cell=1234 target_dir=/foo
Content-Type: text/plain; charset=ISO-8859-1

Cell is 1234 and Target Dir is /foo
[download]

BTW, why do you import the param subroutine? With the object interface of CGI, you don't need to import any subroutines.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

Like choroba says it should work, but,

What webserver are you using (mapache moo.A.1245?? ) What CGI.pm are you using?

Hehehe, CGI.pm, never ceases to confuse :) delete this stuff from your program

### use CGI qw(:standard); ## REMOVE MYSTERY CODE
### use CGI 'param';       ## REMOVE MYSTERY CODE
[download]

Then try this program in your browser and see what you get

#!/usr/bin/perl --
use strict;
use warnings;
use CGI;
my $store = CGI->new;
my $cell = $store->param('cell');
my $target_dir = $store->param('target_dir');
print $store->header;
print $store->escapeHTML( $cell );
print '<hr>';
print $store->escapeHTML( $target_dir );
print '<hr>';
DebugCGI( $store);
exit 0;


sub DebugCGI {
    my( $cgi ) =  @_;
    $cgi ||= CGI->new;
    binmode STDOUT, ':encoding(UTF-8)';
    $cgi->charset( 'UTF-8' );
    print $cgi->header( -charset => 'UTF-8' );
    print $cgi->start_html,
      $cgi->b( rand time, ' ', scalar gmtime ),
      '<table border="1" width="%100"><tr><td>',
      $cgi->Dump,
      '</td>',
      '<td><div style="white-space: pre-wrap; overflow: scroll;">',
      $cgi->escapeHTML( DD( $cgi ) ),
      '</div></td></tr></table>',
      CGI->new( \%ENV )->Dump,
      $cgi->end_html;
} ## end sub DebugCGI

sub DD {
    require Data::Dumper;
    return scalar Data::Dumper->new( \@_ )->Indent( 1 )->Useqq( 1 )->D
+ump;
} ## end sub DD


__END__
[download]

Take special note of the value of QUERY_STRING