Adding a high resolution illustration to an existing illustration


I am trying to add a high resolution illustration to an existing illustration that only has the low res in the database. I have tried the following code.


$myFilePath = "C:\sdl\exportMissHighRes\=GUID-069E3225-F65B-402B-9F28-CF4BC39D413A=1=en-US=Low.png" # Template which is used to create a language level
$ishMetadataFields = Set-IshMetadataField -IshSession $ishSession -Name "FTITLE" -Level "Logical" -Value "snippet_concept" `
        | Set-IshMetadataField -IshSession $ishSession -Name "FCHANGES" -Level "Version" -Value "updated to high res" `
        | Set-IshMetadataField -IshSession $ishSession -Name "FSTATUS" -Level "Lng" -Value "Draft" `
        | Set-IshMetadataField -IshSession $ishSession -Name "FAUTHOR" -Level "Lng" -Value "" `
        | Set-IshMetadataField -IshSession $ishSession -Name "FRESOLUTION" -Level "Lng" -Value "High"
$ishObject = Add-IshDocumentObj -IshSession $ishSession -FolderId "287444" -IshType "ISHIllustration" -Lng "en-US" -Metadata $ishMetadataFields -Edt "EDTPNG" -FilePath $myFilePath



I get the following error: Add-IshDocumentObj : [-108001] Usage of field "FRESOLUTION" during a "CREATE" action is not allowed.  

if I block the line with FRESOLUTION it get this error: Add-IshDocumentObj : [-144] Invalid or no resolution specified. [144;InvalidResolution]

Is there a way to add a high res version of an illustration to an existing logicalid?