Exchange - Programmatically Created Mailbox Can't Access Users' Calendars - vb.net

Question

I've been using a web application I've written to remotely create users/mailboxes on my Exchange server. However, users created using this method have been unable to see other users' calendar information within the same organization. Did I forget some important parameter?
I'm almost certainly not following best practices, but I essentially craft a command and send that to the Exchange powershell for my organization, like so:
Dim runspace As Runspace
runspace = ConnectToExchange()
Dim command = New Command("New-Mailbox")
command.Parameters.Add("Name", firstName & " " & lastName)
command.Parameters.Add("Alias", userName)
command.Parameters.Add("OrganizationalUnit", ou)
command.Parameters.Add("UserPrincipalName", userName & "#" & domainName)
command.Parameters.Add("SamAccountName", userName)
command.Parameters.Add("FirstName", firstName)
command.Parameters.Add("Initials", "")
command.Parameters.Add("LastName", lastName)
command.Parameters.Add("Password", securePassword)
command.Parameters.Add("ResetPasswordOnNextLogon", True)
command.Parameters.Add("Database", db)
command.Parameters.Add("AddressBookPolicy", abp)
runspace.Open()
Dim pipeline = runspace.CreatePipeline()
pipeline.Commands.Add(command)
' Execute the command
Dim results = pipeline.Invoke()
runspace.Dispose()
I should mention that I've reviewed the docs, but the only thing that stands out to me is the Sharing Policy parameter. Reviewing now..
EDIT: I have the same Sharing Policy applied as a test user I've just created. I can view others calendars, but the test user cannot.
SECOND EDIT: I ran the following cmdlets for both my normal account (which can see calendars) and the test account (which cannot see calendars):
Get-Mailbox identity.here | Format-List * | Out-File C:\Users\MyName\Desktop\file.txt
I then ran these through a diff tool and found the differences. There was nothing notable that would cause this issue! I don't know where to turn to next.

Answer 1

please run the following CMDlet on both accounts:
Get-MailboxFolderPermission -Identity john#contoso.com:\Calendar
Please note that the "Calendar" part seems to depend on your Exchange installation language (in German its "Kalender" for example).
If i get you right your account probably has AccessRights:{PublishingEditor} set.
If so run the following CMDlet on the account that doesnt have access:
Set-MailboxFolderPermission -Identity john#contoso.com:\Calendar -User Default -AccessRights Reviewer
Hope that helps
Paul