Combobox Dynamic Name Range

how to control the contents of one combobox based on the selection made in another combobox. But, for some reason, ComboBoxTime1 (as shown in the code below) will only display the first item in the Dynamic Named Range when the user clicks on the pull-down arrow. The Named Range is consistent in size (4 cells) for each of the selection options in ComboBoxDay1. why only the first of four options are displayed in the second combobox?

Also, when a selection is made in the first combobox, the second combobox immediately displays the first item in the Dynamic Named Range (the one selection option it allows). I would prefer for it to remain blank until the user has selected an item from the pull-down list.

Private Sub ComboBoxDay1_Change()
Dim strRange As String
If ComboBoxDay1.ListIndex > -1 Then
strRange = ComboBoxDay1
strRange = Replace(strRange, " ", "_")
With ComboBoxTime1
.RowSource = vbNullString
.RowSource = strRange
.ListIndex = 0
End With
Else
LblTime1.Caption = "Time 1:"
End If
End Sub