adding text to end of string

This would seem to be an easy solution but....

The setup. I'm trying to search offline eventlogs. There are multiple logs of a server just different weeks.
These logs are located on a remote storage location.
I can get the directory using

> $logarchivepath = get-childitem $logarchiveuncpath\ -Recurse | ?{ $_.PSIsContainer } | Sort-Object | Select-Object FullName  

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I can get the filenames using

> $filenames = get-childitem $logarchiveuncpath\ -Recurse | Select -exp Name

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The result of $logarchivepath is ;

\\jill\it-dept\Docs\Docs\Monthly IT Reports\EventLogBackup\temp\WIN10SERVER-Logs-02031502

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>>>>> There are about 20 servers with at least 4 folders each<<<<<<<

The result of $filenames is:

Application.evt
ADAM (VMwareVCMSDS).evt
System.evt
Internet Explorer.evt
Active Directory Web Services.evt
Windows PowerShell.evt
HardwareEvents.evt
Key Management Service.evt
Security.evt

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>>>>>>>>>>>Again this list is repeated for each server in the above list.<<<<<<<<<<<<<<<<<<

This is my code;

$log = "Security.evt"
	foreach ($computer in $strcomputer)
	{
        $lpb = 1
	 $computer
        $logarchivepath = get-childitem $logarchiveuncpath\ -Recurse | ?{ $_.PSIsContainer } | Sort-Object | Select-Object FullName 
        $filenames = get-childitem $logarchiveuncpath\ -Recurse | Select -exp Name
        $logarchivepath 
           foreach ($logfile in $logarchivepath)
            { 
            foreach ($filename in $filenames)
                {
 		        $result = Get-Winevent -Path $logfile -Logname "$log" -oldest | where-object {$_.Id -eq 517 -or $_.Id -eq 1102}
                $result
                pause
                }
            }
	$lpa = $lpa + 1
	}

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>>> The pause statement is for troubleshooting<<<<<

I'm getting the following error;

Get-WinEvent : Parameter set cannot be resolved using the specified named parameters.
At line:179 char:22
+                  $result = Get-Winevent -Path $logfile -Logname "$log" -oldest | where ...
+                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [Get-WinEvent], ParameterBindingException
    + FullyQualifiedErrorId : AmbiguousParameterSet,Microsoft.PowerShell.Commands.GetWinEventCommand

I "think" my problem is that I need a trailing "\" in my path statement but not sure. And I've tried just about every conceivable method to add a trailing "\" to the path statement but haven't been successful.

Or is there something else I've missed?