Call sheet embedded sub from another sheet embedded sub

Hi, I trigger this code via a Command Button (ActiveX Control). CommandButton3_Click() is stored in a sheet not a module, BAML_HYSpread is stored in another sheet not a module.

Private Sub CommandButton3_Click()

Call BAML_HYSpread


End Sub

"Call BAML_HYSpread" gives an error: "Compile error: Sub or Function not definded"

There is no error by storing "BAML_HYSpread" in a module.

Does Excel not allow to call from sheet to sheet in general?

If so, why? In my view this would be very helpful due to organizational reasons.

Best,
Lloyd