#136 3 level formula reference cause #NUM! error

[Trung Tran]

A1: =1
A2: =2
B1: =A1+A2
B2: =A1+A2
B3: =SUM(B1:B2)

- B3=6 -> correct, change A1 to =1+3, B3 will turn to #NUM! (Not a number) -> error
- B2: =A1*A2, B3: =B1+B2 -> java.lang.Object exception popup.