<SOLVED>Dereferencing arrays

[divitto]

<SOLVED> Let me explain, I know that @$arrayRef will return the array that the reference is pointing to. I've also tried @{ $arrayRef } as well. i've tested both of these scenarios in a seperate script just to make sure they work on my machine and they do. (not suprisingly) When i try to run my actual script (below) i get a weird error, that has stumped me for the last two days. I could use some wisdom, Thank you in advance. here's the code:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

#protos
sub mergeSort( \@ );

my @unsortedData = ( 5, 4, 7, 2, 1, 3, 6, 9, 8, 10 );

# show the original data to screen
for( @unsortedData ) {
    print "$_  ";
}
print "\n";

my $sortedData = &mergeSort( \@unsortedData );

# show the new data to screen
for( @$sortedData ) {
    print "$_  ";
}
print "\n";

### dereferencing of arrays isnt working in below method

sub mergeSort( \@arrayRef ) {
    my ( $data ) = @_;

    if( @$data < 2 ) { return $data; }  # if there is less then two it
+ems it's already sorted!!
    
    use integer;
    #split the array into two parts
    my $middle = @$data / 2; 
    print "middle: $middle\n";
    
    my @leftSide = (); 
    print "LeftSide:\n";
    for( my $i = 0; $i < $middle; $i++ ) {
        @leftSide[$i] = @$data[$i];
        print "@leftSide[$i] ";
    }
    print "\n";
    my @rightSide = (); 
    print "RightSide:\n";
    for( my $i = $middle; $i < @$data; $i++ ) {
        @rightSide[$i - $middle] = @$data[$i];
        print "@rightSide[$i - $middle] ";
    }
    print "\n";
    &mergeSort( @leftSide );
    &mergeSort( @rightSide );
    &merge( @leftSide, @rightSide, $data );
    return $data;
}

sub merge {
    my ( @groupA, @groupB, $dataRef ) = @_;
    my $i = 0; my $j = 0; my $k = 0;
    
    while( $i < @groupA && $j < @groupB ) {
        if( @groupA[$i] <= @groupB[$j] ) {
            @$dataRef[$k] = @groupA[$i];
            $i++;
        }
        else {
            @$dataRef[$k] = @groupB[$j];
            $j++;
        }
        $k++;
    }
    while( $i < @groupA ) {
        @$dataRef[$k] = @groupA[$i];
        $i++;
        $k++;
    }
    while( $j < @groupB ) {
        @$dataRef[$k] = @groupB[$j];
        $j++;
        $k++;
    }
}

I was trying to implement a merge sort. (i'm aware the default for perl's sort() is a merge sort. thats not the point) the problem comes from my mergeSort subroutine either when i test that the array is less then 2 or when i try to get the size of the array for my $middle calculation. the output i get is:

5  4  7  2  1  3  6  9  8  10  
middle: 5
LeftSide:
5 4 7 2 1 
RightSide:
3 6 9 8 10 
Can't use string ("5") as an ARRAY ref while "strict refs" in use at m
+ergeSort.pl line 34.

it's probably just me getting lost in context but i don't think im using a string as an array reference, any ideas?