2010 public folder migration

Hi, I'm using http://technet.microsoft.com/en-us/library/jj150486(v=exchg.150).aspx to migrate my 500GB of Public Folders from 2010 to 2013. 

I'm up to Step 3: generate the .csv files and I've created the "name to folder size mapping file". I'm trying to perform the next step using the script:

.\PublicFolderToMailboxMapGenerator.ps1 <Maximum mailbox size in bytes> <Folder to size map path> <Folder to mailbox map path>

But regardless of running this on Exchange 2010 or 2013, I get the following result an absolute ton of these:

You cannot call a method on a null-valued expression.
At C:\PFMigration\PublicFolderToMailboxMapGenerator.ps1:67 char:59+         foreach ($familyMember in $folder.FolderName.Split <<<< ('\', [System.StringSplitOptions]::RemoveEmptyEntries
))+ CategoryInfo          : InvalidOperation: (Split:String) [], RuntimeException+ FullyQualifiedErrorId : InvokeMethodOnNull

I do not have any \ in my csv file. I'm thinking of skipping this script and manually create a csv file as such:

I gather this would create 5 public folder mailboxes, one for each office and all existing subfolders to the \ipm_subtree\officeX would be included in that public folder mailbox. Would this approach work? One office has several mail enabled public folders in Exchange 2010, do I need to separate those folders into different PF mailboxes?

Or am I completely off track here, should I actually be creating 1 PF mailbox for every existing folder? I got over 11 thousand folders according to my name-to-folder mapping file.

Any thoughts on the error message on the script above or on how to split up the 2010 public folders into mailboxes would be greatly appreciated. 

Thanks.