ELVIS III -VPS OUTPUT ERROR

[Gan.Tang]

The purpose of this program is to make the VPS output negative voltage。However, the actual output cannot obtain negative voltage。

when i run this vi and use the DC voltage gear of the multimeter, the measured output is 0

i use labview 2019 sp2 and elvis iii toolkt 2.2，it is a bug or other？

anyone knows？

However, the actual output cannot obtain negative voltage