calling a subroutine from another subroutine

[abcdefg]

Hi Perlmonks, I am stuck with a very basic thing in perl code being newbie to coding.

my $usage       = "
Usage: $scriptname (-type<type> -OIMID <oimid> -version <version_numbe
+r> -out <filename>  ) 
           -type <type>              :A|B
          -version <version_number>  :Required.Minimum Security Versio
+n Number.
       -OEMID <oemid>             : Required.
       -out <filename>          : Required.              
          
";

my %opts;
$result = GetOptions ("type=s"   => \$type,
                      "version=i" =>\$version_number,
              "OIMID=s" =>\$oimid,
                      "out=s"   => \$filename);


if ($type eq "A"){

    &Add() ;
}
elsif ($t eq "B"){
    &Sub();
}
else {
    die "Unhandled  option.\n";
}

sub StingtoNum()
{
if ($oimid = "Google")
{

return "01";
}
elsif ($oimid = "DELL")

{
return "02";
}
else
{
return "00";
}
}



sub Add()    {

    $oim = &StingtoNum;
        $zero="00"
    $Version_Info = $oim.$zero.$version_number;
        
}

$

Now when i run this program,inspite of whatever I give the value of oimid in commandline,it takes the value of oim in Add as "01".I expect if I give oimid as dell it should give 02 for oim. What am I doing wrong? Thanks in Advance for help.