The subform control is the control on the main form that houses the subform. Its name is the name to reference in code and not the subform name. If the subform control, and the subform have the same name, that is okay but it isn't necessary. If the subform control and the subform have different names then you must remember to refer to the subform control , and not the subform itself, within your code. For example, if you have a subform container named subform1 on a main form named frmMain and your subform within the control is named sfrm_test your code to refer to a text box named txtTest on the subform would be:
Forms!frmMain.subform1.Form.txtTest = "Whatever"