I solved it with this code
Private Sub ComboBox1_Change()
' Compares ComBox Text with text in sheet
DateFound = False
For I = 11 To 100
If UserForm1.ComboBox1.Text = (Sheets("Calculation").Range("A1").Offset(I, 0).Text) Then
DateFound = True
Set mc = ActiveSheet.Range("A1").Offset(I, 0)
Exit For
End If
Next I
' AddressFound returns Range of matching text
If DateFound Then AddressFound = mc.Address Else MsgBox "No valid data for this period!", vbExclamation
' Returns data from column in same row as matching text
UserForm1.Naph.Text = (Sheets("Calculation").Range(AddressFound).Offset(0, 1).Text)
UserForm1.E.Text = (Sheets("Calculation").Range(AddressFound).Offset(0, 2).Text)
UserForm1.A.Text = (Sheets("Calculation").Range(AddressFound).Offset(0, 3).Text)
End Sub