Here is how you might get into trouble if you do not follow
Roger's advice:
....type "=" and point to first cell that you wish to extract data
from...
You might instead fill in the Function Arguments of GETPIVOTDATA().
Assume your PT is located at A1 and looks like this:

Sum of Value Column
Row 2/1 2/2 2/3 Grand Total
DE 6 2 1 9
EA 4 6 4 14
EP 6 7 7 20
FM 4 9 5 18
GK 7 2 2 11
JH 3 1 9 13
KM 4 9 6 19
MG 2 4 4 10

If you want to extract the 20 in the Grand Total, you might write:
=GETPIVOTDATA("Value",E3:E10,"Row","EP")
which will give you the correct result.
However, if you unselect Column 2/3, you get #REF!
If you follow Roger's method, you get this formula:
=GETPIVOTDATA("Value",A1,"Row","EP")
and the result will be the row Grand Total, independent of
the number of columns.