Why not like thus:
ExcelUtil.pm 

package ExcelUtil;
use warnings;
use strict;
use vars qw(@ISA @EXPORT);

@ISA    = qw(Exporter);
@EXPORT = qw(writeCell);

sub writeCell {
    my ( $obj, $row, $col, $str ) = @_;
    $obj->write( $row, $col, $str );
}

1;

[download]
testExcel.pl 
use warnings;
use strict;
use Spreadsheet::WriteExcel;
use ExcelUtil;

my $wrk_bk  = Spreadsheet::WriteExcel->new('sample.xls');
my $wrk_sht = $wrk_bk->add_worksheet('new_sheet');

writeCell( $wrk_sht, 1, $_, "Testing, Row-1, Col-$_" ) for 1..5;

[download]
Update:
Why even calling the subroutine within it module like you did in your "ExcelUtil.pm" like this
writeCell(1, 2, "testing, Row-1, Col-2");
With the code shown above you can even do like this: writeCell( $wrk_sht, $_, 1, "Testing, Row-$_, Col-1" ) for 1..5; And it still works for you.

If you tell me, I'll forget.
If you show me, I'll remember.
if you involve me, I'll understand.
--- Author unknown to me

In reply to Re: "write" problem with "Spreadsheet::WriteExcel" Module by 2teez
in thread "write" problem with "Spreadsheet::WriteExcel" Module by kiranv

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