I would like to set up a lookup table. when I enter a value in the
spreadsheet, it will find the match value on the column A and print out the
value of column B.

See below
A B
A-01 10.5
A-02 5.6
A-2C 21.2
A-13 11.6

I used lookup function. If the entry is A-2C, the result shows 11.6 instead
of 21.2. Anyone can tell me why? How can I fix the problem? Besides, I
would like to set a function. If my entry does not exist in the table, e.g.
A-1B, I would like to show a "NA" in the result column so I know the input is
incorrect. Can you tell me how to do it?
Thanks.