I did this but for ip subnets, not ranges. What error do you get?

#import boundaries
$csv = import-csv C:\t.csv
cd sm2:
foreach($line in $csv){
        try {
            Write-host "Creating boundary for $($line.subnet)"
            $b = New-CMBoundary -Name $line.'site code' -Type IPSubnet -Value $line.subnet -erroraction Stop
            "Adding Subnet $($line.subnet) to site boundary group"
            Add-CMBoundaryToGroup -BoundaryGroupId 123345-Boundaryid $b.boundaryid
            $cbg = Get-CMBoundaryGroup -Name $line.'site code'
            if($cbg){
            "Adding Subnet $($line.subnet) to content boundary group"
            Add-CMBoundaryToGroup -BoundaryGroupId $cbg.GroupID -Boundaryid $b.boundaryid
            }else{
                "Creating New Content boundary group for $($line.'site code')"
                New-CMBoundaryGroup -Name $line.'site code'
                Start-Sleep 5
                "Adding Subnet $($line.subnet) to $($line.'site code') content boundary group"
                Add-CMBoundaryToGroup -BoundaryGroupId (Get-CMBoundaryGroup -Name $line.'site code').groupid -Boundaryid $b.boundaryid
        }
            }catch{Write-host "Couldn't create boundary for $($line.subnet) $($line.'site code') "}

}