Change Last Writing Date using date in file name - powershell

Question

I would like to change the Last writing date of several CSV files using the dates contained in the names of the different files
Example :
Input : File_20221210085032.CSV (LastWriteTime = 25 October 2022 16:54:25)
Output :(LastWriteTime = 10 December 2022 08:50:32)
In that extent i wrote a code based on my knowledge and some help from internet, this code should do what i want to achieve however i get some errors and i cannot find the errors.
Please find below my code :
cls
$Foldober = 'D:\Bob\Test'
$DateFormat = "yyyymmddhhmmss"
$FileList = Get-ChildItem -LiteralPath $Folder -Filter '*.csv' -File
foreach ($FL_Item in $FileList) {
$Null = $FL_Item.BaseName -match '_\d{14}'
$DateString = $Matches.DateString
$date_from_file = [datetime]::ParseExact($DateString, $DateFormat, $Null)
$FL_Item.CreationTime = $date_from_file
$FL_Item.LastWriteTime = $date_from_file
$FL_Item.LastAccessTime = $date_from_file
# show the resulting datetime info
'=' * 20
$CurrentFileInfo = Get-Item -LiteralPath $FL_Item.FullName
$CurrentFileInfo.FullName
$CurrentFileInfo.CreationTime
$CurrentFileInfo.LastWriteTime
$CurrentFileInfo.LastAccessTime
}
I get the following error
Exception calling "ParseExact" with "3" argument(s): "String was not recognized as a valid DateTime."
At C:\Users\Bob\Desktop\Script\test.ps1:15 char:5
+ $date_from_file = [datetime]::ParseExact($DateString, $DateFormat ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : FormatException
Update #2
After having got ridden of $null in the ParsExact as suggested i get the following errors :
cls
$Foldober = 'D:\Bob\Test'
$DateFormat = "yyyymmddhhmmss"
$FileList = Get-ChildItem -LiteralPath $Folder -Filter '*.csv' -File
foreach ($FL_Item in $FileList) {
$Null = $FL_Item.BaseName -match '_\d{14}'
$DateString = $Matches.DateString
$date_from_file = [datetime]::ParseExact($DateString, $DateFormat)
$FL_Item.CreationTime = $date_from_file
$FL_Item.LastWriteTime = $date_from_file
$FL_Item.LastAccessTime = $date_from_file
# show the resulting datetime info
'=' * 20
$CurrentFileInfo = Get-Item -LiteralPath $FL_Item.FullName
$CurrentFileInfo.FullName
$CurrentFileInfo.CreationTime
$CurrentFileInfo.LastWriteTime
$CurrentFileInfo.LastAccessTime
}
Cannot find an overload for "ParseExact" and the argument count: "2".
At C:\Users\Bob\Desktop\Script\test.ps1:15 char:5
+ $date_from_file = [datetime]::ParseExact($DateString, $DateFormat ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodCountCouldNotFindBest
Exception setting "CreationTime": "Cannot convert null to type "System.DateTime"."
At C:\Users\Bob\Desktop\Script\test.ps1:17 char:5
+ $FL_Item.CreationTime = $date_from_file
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Thanks in advance for your help. Best regards