get_all_software_status returns emtpy chassis_slot_id and install_volume value

here is snippet of Perl script to show software status on VIPRON 2400

 

$soapResponse = $SoftMgmt->get_all_software_status();

 

&checkResponse($soapResponse);

 

my @status = @{$soapResponse->result};

 

 

foreach my $softstatus (@status) {

 

my $InstallationID = $softstatus->{'InstallationID'};

 

my $slot_id = $InstallationID->{'chassis_slot_id'};

 

my $install_volume = $InstallationID->{'install_volume'};

 

my $product = $softstatus->{'product'};

 

my $version = $softstatus->{'version'};

 

my $build = $softstatus->{'build'};

 

my $base_build = $softstatus->{'base_build'};

 

my $active = $softstatus->{'active'};

 

my $edition = $softstatus->{'edition'};

 

my $status = $softstatus->{'status'};

 

print "slot id $slot_id product $product version $version build $build base build $base_build active $active edition $edition status $status\n";

 

}

 

I got result as:

 

slot id install_volume product BIG-IP version 11.2.0 build 2451.0 base build 2446.0 active 0 edition status complete

 

slot id install_volume product BIG-IP version 10.2.1 build 511.156 base build 297.0 active 0 edition status complete

 

slot id install_volume product BIG-IP version 11.2.0 build 2553.0 base build 2446.0 active 1 edition status complete

 

slot id install_volume product BIG-IP version 10.2.1 build 511.8 base build 297.0 active 0 edition status complete

 

slot id install_volume product BIG-IP version 10.2.1 build 511.8 base build 297.0 active 0 edition status complete

 

slot id install_volume product BIG-IP version 11.2.0 build 2451.0 base build 2446.0 active 0 edition status complete

 

slot id install_volume product BIG-IP version 11.2.0 build 2553.0 base build 2446.0 active 1 edition status complete

 

slot id install_volume product BIG-IP version 10.2.1 build 511.156 base build 297.0 active 0 edition status complete

 

as you can see, slot id and install_volume are empty, am I missing something simiple?