Hi chungley2000 and welcome to the monastery,

I was happy to see your post, because I've been thinking about working up a Tk project. It helps for you to specify in code what modules you use. There can be some overlap in cpan resources in some namespaces. It seems that I didn't have Tk, if that is the module you use. It was a truly eye-popping install. At one point, the screen was covered in camels.

I state without proof that I think all contemporary perl should be written with "strictness." I achieve this by the line use 5.011; . Then I just took wild guesses for values in order to get the script to compile. Then I can hit it with perltidy to make it legible. The idea is that you come up with some self-contained example such that it can be run:

$ ./1.tk.pl 
Can't call method "title" on an undefined value at ./1.tk.pl line 7.
$ perltidy -i=2 -b 1.tk.pl
$ cat 1.tk.pl
#!/usr/bin/perl -w
use 5.011;
use warnings;

use Tk;
use Data::Dumper;
my $mw1->title("CMVC File Retriever");

#-----------------------------------------------------------------
# Set up two frames:
#    - $frameTop    - contains radio buttons for selecting table.
#    - $frameBottom - contains button to quit without update.
#-----------------------------------------------------------------
my $update   = undef;
my $frameTop = $mw1->Frame(
  -label       => "QUERY Table  (Last update as of  $update)",
  -relief      => 'groove',
  -borderwidth => 1
)->pack( -side => 'top', -fill => 'both' );
my $table = "fileview";    # default table (turns radio button on)
$frameTop->Radiobutton(
  -text     => "file table",
  -value    => "fileview",
  -variable => \$table
)->pack( -side => 'left' );

### Skipping some of the lines...

my $frameBottom->Button(
  -bg      => 'green',
  -text    => "Get Files",
  -anchor  => 'center',
  -command => \&getSelection
)->pack( -side => 'left' )
  if $table eq "fileview";

### Skipping more of the lines...
my ( $rows, $cols, $arrayVar ) = ( 10, 5, undef );
my $t = $frameTop->Scrolled(
  'Spreadsheet',
  -rows          => $rows,
  -cols          => $cols,
  -width         => 150,
  -height        => 10,
  -titlerows     => 1,
  -titlecols     => 2,
  -rowtagcommand => \&rowSub,
  -coltagcommand => \&colSub,
  -selectmode    => 'extended',
  -variable      => $arrayVar,
  -selecttitle   => 1,
);
my ( $currentText, $activeText ) = ( "current", "active" );

$t->configure(
  -browsecommand => sub {
    my ($index) = @_;
    $currentText = $index;
    $activeText  = $t->get($index);
  }
);

$t->configure(
  -validate        => 1,
  -validatecommand => sub {
    my ( $row, $col, $old, $new, $index ) = @_;
    $activeText = $new;
    return 1;
  }
);
my $results = "not much yet, but started writing code....";
###
### This here is interesting since I think getting selection
### should be easy.  I would expect selectioncommand is meant
### to be used to "extend" the default behavior...  But I don't
### see a real problem with this approach.
###
$t->configure(
  -selectioncommand => sub {
    my ( $NumRows, $Numcols, $selection, $noCells ) = @_;
    $results = $selection;    # assign results to var to read later
    print "DEBUG:  I am here at selectioncommand with results = $resul
+ts,\n";
    return $selection;        # NOT sure where this is returned, so as
+sign above
  }
);

### Skip again to where we are trying to "access" the
### selection's results:

#-----------------------------------------------------------------
# Subroutine to get the selected data and copy it to a user dir
#-----------------------------------------------------------------
sub getSelection {

  #-----------------------------------------------------------------
  # Get selected item and parse into values.
  #-----------------------------------------------------------------

  ### The program was meant to operate on this global $results,
  ### but it is empty...
  ### It seems that selectioncommand never got executed.
  ### What is even more weird for me is that out of the 15/20
  ### different tests that I ran to try to debug this, "twice"
  ### (and I don't know how to replicate it), the
  ### selectioncommand executed some seconds AFTER.
  ### I tried explicitly declared $results as a global variable
  ### by adding "our $results;" before the use in this AND also
  ### in selectioncommand's subroutine.
  ### The other thing that I tried is do use $table->curselection(),
  ### but I don't know how to use that properly; I tried
  ### $table->curselection() and $frameTop->curselection(),
  ### but they failed.

  print "get Selection results are , $results,\n";    # TESTING
  print Dumper($results);                             # TESTING
}
$
[download]

The first problem is the first line, line 7 in this listing. Start tracking your values. A say statement after lines when values are set keeps bad ones from propagating.

If your code is too long to post here, put it on github and post a link to it.

I hope this helps, and I'm grateful to have the perl community helping to solve problems for me.