Thanks you very much for suggestion from SamT and Aussiebear.
I change condition from "If .....then" to "If not......then"
Dim a, b As Long
Dim sCrit As String
Dim tCrit, uCrit As Long
Dim vCrit, wCrit As String
Dim lbtarget As MSForms.ListBox
Dim rngSource As Range
Set rngSource = Worksheets("Sheet2").Range("A2:I1000")

tCrit = ComboBox3.Value
With Me.ListBox1
.ColumnCount = 9
.ColumnWidths = "80;80;80;0;0;110;80;0;30"
.List = rngSource.Cells.Value
For a = .ListCount - 1 To 0 Step -1
If Not UCase(.List(a, 0)) >= tCrit Then
.RemoveItem a
End If
Next a
End With

uCrit = ComboBox4.Value
With Me.ListBox1
For a = .ListCount - 1 To 0 Step -1
If Not UCase(.List(a, 0)) <= uCrit Then
.RemoveItem a
End If
Next a
End With
It is now working.

And I will code to find dates between two dates ( start and end date) .

Anyone can suggest or give some example?