Dual Data Validation Dropdown Lists

I'm trying to create a cell with multiple dropdown lists in E4 depending on a value from another drop down list in B4. Both E4 dropdown lists are named cell ranges RV_MECHANISM and VALVE_OPERATING_MECHANISM_TYPE. I know how to do this in Data Validation using an IF formula, however, that's not quite "bullet proof" or "idiot proof" enough.

I'm attempting to create a macro to load only the appropriate dropdown list in E4 as called for by B4.

I recorded the Data Validation dropdown lists using the macro recorder, then searched through all appropriate posts I could find at MrExcel and attempted to write the appropriate macro code as follows;

Sub RVorMECHTYPE()
With Selection.Validation
.Delete
.Add Type:=xlValidateList
If Range("$B$4").Value = "RV" Then
ValList.RV_MECHANISM
Else
ValList.VALVE_OPERATING_MECHANISM_TYPE
End With

Range("E4").Select

End If
End Sub

Compile error: End With without With

That's as close as I can get ... can one of you kind souls direct my macro coding paths and offer up the correct code for accomplishing this task.