You should not enclose a variable name in double quotes
& is for concatenating two strings

e.g.

Name="tom"
MsgBox "Hello! " & Name

The output is
Hello! Tom

When you need to display a quote, you need to use two quotes

e.g.

s="test "" quote"
MsgBox s

The output is
test " quote

esbee wrote:
Many thanks. It's working fine. I didn't know that even '&my_last_row&'
should be enclosed in double quotes. Thanks for this knowledge.