Pro/E VBA newbie

(If this is a duplicate, please ignore - I didn't see the original in the Forum.)

I get the following Compile Error "Argument not optional." What argument is it missing?

Sub async_test()


Dim asyncConnection As IpfcAsyncConnection
Dim cAC As CCpfcAsyncConnection
Dim session As IpfcBaseSession
Dim descModel As IpfcModelDescriptor
Dim descModelCreate As CCpfcModelDescriptor
Dim model As IpfcModel

Dim sessionid As IpfcConnectionId

Set sessionid = New CCpfcConnectionId

Set cAC = IpfcAsyncConnection

Set sessionid = CCpfcAsyncConnection.GetConnectionId()

Set asyncConnection = cAC.ConnectById(sessionid) <<<<<--Highlights ".ConnectById" including the leading dot.

Set session = asyncConnection.session


End Sub