AutoCAD Inventor :: Calling Sub From Different Document

In an object type Project I have a form with a button that calls another sub of the same form, the code looks something like this:

Private Sub CommandButton1_Click ()

'Set a Part Document as active document
Dim oDoc As Inventor.PartDocument
Set oDoc = ThisApplication.Documents.Open ("C: Users oZteC Documents Inventor Experiment part1.ipt", True)
oDoc.Activate

'Call "ModelParameters" within the same form
Call ModelParameters

End Sub
____________________

Public Sub ModelParameters ()
....
End sub

I want to move the sub "ModelParameters" to the object type PartDocument, the problem is when I move it the call doesn't work.
I want to run something like this:

ApplicationProject> Form> ClickButton ----> call to ----> DocumentProject> ThisDocument> Sub