Getting error while executing VBA Code

Hi I am getting error while executing below code :-> Compile error : User-defined type not defined

Sub Test()

Dim pUID As New UID
Dim pCommand As ICommandItem
pUID.Value = "myLibrary.myClass"
Set pCommand = m_papp.Document.CommandBars.Find(pUID)
pPcommand.Execute

End Sub

Can any tell me is it possible to create PUID as UID instance and pCommand as ICommandItem.

In excel VBA its giving me error.