Calling function defined inside powershell script

Not sure if I'm doing this right, as it's only the 3rd powershell script I've ever written, so apologize for such a basic question.

I have a loop that needs to be run in two to three different areas. Rather than repeat the code over and over, I'd like to place it in a defined function and call from inside the script.

The function uses a simple switch statement to get the description of a local group, then returns the string variable holding the description.

The function seems to process fine, however after the return statement I get the following error message

Exception setting "description": "The following exception occurred while retrieving member "description": "The group name could not be found.

This is a pretty basic feature of Powershell, so I'm not sure what's going on.

Below is the complete script. The code in the try block calls the function createGroupAndUsers, which in turn calls the function addDescription, which is where the error is occurring.

#HERE IS THE FUNCTION THROWING THE ERROR
Function addDescription($groupName)
{
    switch($groupName)
    {
        "WebDevelopers"        {$description = "Developers for this Web Server.  They have RDP rights and update rights to the webcontent share." }
        "AgentPaymentUpdater"  {$description = "Used by OKeeffe WCF Web Service to update DSS"}
        "AgencyCloneRequestor" {$description = "Used by OKeeffe WCF Web Service to clone agent data from DSS"}
        "WynsureServiceInquiry"{$description = "Used by AgentInformationService WCF Web Service to query DSS"}
        "BundleInquiry"        {$description = "Used by AgentInformationService WCF Web Service to query DSS"}
        "BundleUpdate"         {$description = "Used by AgentInformationService WCF Web Service to query DSS"}
        "DistributorInquiry"   {$description = "Used by AgentInformationService WCF Web Service to query DSS"}
    }   

    #return statement throws exception
    return $description
}

#ABOVE FUNCTION CALLED BY THIS ONE
Function createGroupAndUsers($groupName, $computerName)
{ 
    #clear variables from previous run
    if($objGroup)
    {
        Clear-Variable $objGroup
    }
    if($Members)
    {
        Clear-Variable $Members
    }
    if($MemberName)
    {
        Clear-Variable $MemberName
    }
    if($tempArray)
    {
        Clear-Variable $tempArray
    }

    #create group and add description
    $objGroup = [ADSI]"WinNT://localhost/$groupName"

    if(-not $objGroup)
    {
        Write-Host "Creating Local Group $groupName" -ForegroundColor green
        $objGroup = $cn.Create("Group", $groupName)
        $objGroup.setinfo()
    }

    Write-Host "Setting Description for Local Group $groupName" -ForegroundColor green
    $objGroup.description = addDescription $groupName
    $objGroup.setinfo()

    #pull group members from remote machine
    $Members = Get-ADGroupMember -Identity $groupName -Server $computerName
    $Members | ForEach-Object {$MemberNames += $_.GetType().InvokeMember("Name", 'GetProperty', $null, $_, $null) + ",";}

    $tempArray = $MemberNames -split ","
    foreach($member in $tempArray)
    {
        Write-Host "Adding $member as user for Local Group $groupName" -ForegroundColor green
        $objGroup.Add("WinNT://DOMAIN/$member, user")
    }
}

#'MAIN' BLOCK OF CODE THAT CALLS ABOVE FUNCTIONS
try{
         #Periscope and OKeeffe
         $computerName = "DEVWB37" 
         $groupArray = @("WebDevelopers", "AgentPaymentUpdater", "AgencyCloneRequestor")

          foreach($groupName in $groupArray)
          {
            createGroupAndUsers $groupName $computerName
          }
 }

catch{
     write-host "Caught an exception:" -ForegroundColor Red
     write-host "Exception Type: $($_.Exception.GetType().FullName)" -ForegroundColor Red
     write-host "Exception Message: $($_.Exception.Message)" -ForegroundColor Red
}