Getting error 400 when click the save file button

I am building a simple excel template that will save and clear a Purchase Order.
However, it always return the error 400 when i click the Save and Clear button which will save the purchase order to public drive. Also, the file path i save is changed to "P:\Sam PO\PO" & Range("L2").Value & ".xlsx" from "K:\Sam PO\PO" & Range("L2").Value & ".xlsx", but I didn't change it myself.

here is my code for the save and clear button, could anyone please tell me what is the cause of error 400 and is there anything wrong with this code?
I tested it on my local environment, I didn't experience any error.

Sub NextInvoice()
Range("L2").Value = Range("L2").Value + 1
Range("B22:L51").ClearContents
End Sub

Sub SaveInvWithNewName()
Dim NewFN As Variant
' Copy Invoice to a new workbook
ActiveSheet.Copy
NewFN = "K:\Sam PO\PO" & Range("L2").Value & ".xlsx"
ActiveWorkbook.SaveAs NewFN, FileFormat:=xlOpenXMLWorkbook
ActiveWorkbook.Close
NextInvoice
End Sub

thank you so much. we figured out why it is causing the error 400 after we add the error catch. it is caused by the local drive.