The code "If Val(ComboBox1) = Sheets("Sheet3").Cells(i,1) " works for the numbers but not for the strings. If, however, I amend the code to:

Code:
Private Sub Frequencies()
For i = 2 To 5
If Val(ComboBox1) = Sheets("Sheet3").Cells(i, 1) Then
TextBox1 = Cells(i, 2)
ElseIf ComboBox1 = Sheets("Sheet3").Cells(i, 1) Then
TextBox1 = Cells(i, 2)
End If
Next i
End Sub
the problem is solved.

So thanks, kaliman79912.