Copy Specific SO Number until next SO Number

Hi, please help me.
I'm trying to copy the SO Number (SO-0001..SO-0467) next to the Voucher Number (10-RV0001, 10-CM0001, 10-DM0002, 10-BY0003 etc.) so i can sort it.

I've used this code, but it didn't work.

Sub Macro1()
    Cells.Find(What:="SO-000*", After:=ActiveCell, LookIn:=xlFormulas, _
        LookAt:=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlNext, _
        MatchCase:=False, SearchFormat:=False).Activate
    Range("A4").Select
    ActiveSheet.Paste
    Range("A5").Select
    ActiveSheet.Paste
End Sub

I'm new to Excel Macros, thank you in advance

PS: here's an example of my worksheet.