PowerShell Function Not Working as Expected

I have the following function:

function GetParameterValue($ParmFile, $ParmName)
{
	$tmp = $ParmFile | where { $_.Key -eq $ParmName } | Select Value
	return $tmp.value
}

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$ParmFile is created outside the function with the following code:

$CSV = import-csv .\Params.csv

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$CSV is what is passed to the function. The call syntax is

$ROOT = GetParameterValue($CSV, "ROOT")

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This is returning an empty string. I know I am reading the data into $CSV because prior code was replicating what I encapsulated into the function and working properly. Is there something I am missing here?