Automatically create folder on SharePoint

In my Access program, I am trying to create a folder if one does not exist on
a Sharepoint site, but I am receiving a permission denied error. I have the
appropriate persmissions to create a folder and I can create one manually
directly on the site. Does anyone know a better way? I am using the
following code:

Public Sub CreateWorkingFolder(ByVal sWorkingDir As String)

Dim fso As New FileSystemObject

If fso.FolderExists(sWorkingDir) = False Then
fso.CreateFolder Path:=sWorkingDir
End If

Exit_CreateWorkingFolder:
Exit Sub

TIA!