Dear PerlMonks, Please help me. This is my first post on SOPM so beg you forgive any indiscretions.
The perl code I have managed to "put together" is not giving me the right answers. Here is a data sample that I want it to process: 
20050526~18:15:06 GMT
20040401~01:12:02 GMT
20060201~00:59:01 GMT
20060401~01:01:01 EST
20040201~10:10:01 -0600
20010901~04:23:05 -0400
20050526~18:15:06 GMT
20040401~01:12:02 GMT
20000101~00:59:01 -0200
19841223~04:22:06 MST

[download]
And here is the perl code cleaned up a bit with PerlTidy
#!/usr/bin/perl -w
use strict;
use Date::Manip;
Date_Init("TZ=EST");    #set TimeZone to Eastern Daylight Savings Time
{
    my $input = $ARGV[0];    #returns filename from command line
    my $thetmz;              #time zone for that line
    my ( $date, $time);      #from file

    chomp $input;                       #strip the carriage return

    sub convertthetmz {
        $datetime = ( "$date" . "$time" )
          ;    #$date and #time from subroutine call and concats them
        $converteddate = ParseDate("$datetime");    #date-time strng
        $converteddate =Date_ConvTZ("$converteddate", $thetmz, "EST" )
          ;    #converts from any tmz to EST
        print("$converteddate~$from~$to\n");
    }

    open( DATAFILE, "$input" )
      || die("Can not open $input:!\n");    #access the file

    while (<DATAFILE>) {
        chomp $_;
        ( $date, $time) = split( "~", $_ );  #split date/time 

        my $testfortmz = substr $time, -3;    #last 4 chars of str
        if ( "$testfortmz" == "-0400" ) {
            $thetmz = "AST";

            convertthetmz( $thetmz, $date, $time, $from, $to );
        }
        elsif ( "$testfortmz" == "-0600" ) {
            $thetmz = "CST";
            convertthetmz( $thetmz, $date, $time, $from, $to );
        }
        elsif ( "$testfortmz" =~ " GMT" ) {
            $thetmz = "GMT";
            convertthetmz( $thetmz, $date, $time, $from, $to );
        }

        else    #this is need to work for some reason
        {
            my $nochangedate;
            $nochangedate = ( ParseDate("$date.$time") );
            print("$nochangedate~$from~$to\n");
        }

    }
    close(DATAFILE);
}

[download]
The result that I get with the above data sample is the following: 
2005052613:15:06
2004033120:12:02
2006013119:59:01
2006040101:01:01
2004020112:10:01
2001090102:23:05
2005052613:15:06
2004033120:12:02
1999123121:59:01
1984122306:22:06

[download]
Some of these are correct but others are I believe wrong.
Shouldn't 20040201~10:10:01 -0600 be 2004020111:10:01 EST since there is only 1 hour difference between -600 and -0500?
Obviously I did something wrong. I would greatly appreciate your assistance! Thank you kindly!

In reply to TimeZone Assistance Requested by Knoperl

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.