SHT15 communication problem

Hi, I have a small project for monitoring temp. and hummidity.
Using Arduino NANO and SHT15 (https://www.sparkfun.com/datasheets/Sensors/SHT1x_datasheet.pdf)

I'm using this library for communication GitHub - practicalarduino/SHT1x: Arduino library to support SHT1x-series (SHT10, SHT11, SHT15) temperature / humidity sensors from Sensirion and my program is the one from examples SHT1x/ReadSHT1xValues.pde at master · practicalarduino/SHT1x · GitHub

data pin=10
sck=11

I'm getting negative values for temp. and hummidity.

Have anybody already experienced this issue ? What could be the problem ?

Thanks for any suggestion.