Powershell CSV Validator

Question

I have the following PS Function for validating CSV files.

The CSV Files are in the format

EmpNo (int), Type (int), StartDate (DateTime), EndDate (DateTime)

And the powershell script verifies the type of each of column value and also validates that there are no duplicate employee numbers. However I assume this can be done in a more "PowerShell-y" way. Feedback welcome.

function Validate-MinimumGuaranteeCSV($file)
{
    $rawdata = Import-Csv $file
    $count = 0;

    $rawdata | ForEach  {  

        $count++
        [ref]$StartDate = Get-Date
        [ref]$EndDate = Get-Date
        [ref]$EmpNo= 1
        [ref]$Type= 1

        if([DateTime]::TryParse($_.StartDate, $StartDate) -eq $false)
        {
            Write-Host "StartDate on Line $count is invalid" 
        }
        if([DateTime]::TryParse($_.EndDate, $EndDate) -eq $false)
        {
            Write-Host "EndDate on Line $count is invalid" 
        }
        if([Int32]::TryParse($_.EmpNo, $EmpNo) -eq $false)
        {
            Write-Host "EmpNo on Line $count is invalid" 
        }
        if([Int32]::TryParse($_.Type, $Type) -eq $false)
        {
            Write-Host "Type on Line $count is invalid" 
        }
    }

    $rawdata | Group-Object -Property EmpNo | 
        Where { $_.Count -gt 1 } | 
        foreach { Write-Host "EmpNo $($_.Group[0].EmpNo) occurs more than once" }
}