use two column values in inputbox to select a row

Helo!

I have a database in excel for devices for each device I have 11 columns! To modify or delete a device I have created 2 inputbox that will ask the user to enter the value of 2 columns: The SN (serial number) and HT (manufacturer)
If the values in each input box correpond to the same row in the database i want to select the entire row and put the selection in a listbox (I've done this job with only one inputbox with the following code):

Sub Imoddevice()
Dim SN As String



SN = InputBox("Enter serial number ", vbOKCancel)


If SN = "" 

If SN = "" And HT <> "" Then
MsgBox " Error in SN  input"
Userinterface.Show
        
Else
For j = Range("E65536").End(xlUp).Row To 1 Step -1
    If Range("E" & j) = SN Then a = Range("E" & j).EntireRow.Select
    a = Selection.Row
Next j

Load moddevice

         moddevice.ListBox2.List = Selection.Value
                  moddevice.Show
End If
End Sub

I want to add another inputbox to ask the user to enter the manufacturer because sometimes two devices can have the same SN!

For example if the SN and HT that the user has entered correspond to the same row, I want to select the row
If the SN correspond to a row and the HT correspond to another row , I want to put an error message that says: "SN or HT error"

Anyone can help??
Thanks!!

here is the excel file if it can helps you: on the interface from left to right:
add device
modify device
delete device
(it is in german because i am doing an intership in a german biomedical company)
Thanks!!
VBA_Database(08.05.2013).xlsm

Why not use a little userform with two input options to get S/N and Manfufacturer name/ number at once?

Yeah I had the same idea! But how you compare the row of both selection ?