Error Running A Script From Another Script in Powershell

I have 2 scripts. One named 2022.ps1 that simply has this:

##Year Driver##
$curDir = Get-Location

& ".\January\Jan2022.ps1"

This code should run the Jan2022.ps1 script which runs fine if I run that on it's own. But when being called from 2022 I get the following error:

Cannot convert null to type "System.DateTime".
At C:\Users\Dummy\Desktop\2022All\January\Jan2022.ps1:47 char:5
+     $regDateCheck = ([DateTime]$regDateCheck).ToString("MM-yyyy")
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidArgument: (:) [], RuntimeException
    + FullyQualifiedErrorId : nullToObjectInvalidCast

Why is this happening? I need to call scripts for the rest of the months as well.