It's not finding TP because it's looking in the first row of copied data, but your new pivot contains an added header 'Sum of Items Value' above the columns headers, which implies there may be something in the columns field.
You really ought to attach the real thing or a more accurate representation of the real thing as a workbook.
A quick fix might be:
UnitsColm = Application.Match("TP", Destn1.Rows(2), 0)
but it would probably mess up elsewhere.
just copy/pastes SourceRng to Destn2
Add the lines:
SourceRng.select
Destn2.Select
before the copying line and step throuigh the code with F8 on the keyboard to see what those areas are.