Strange behavior solver app

[tecnovelez]

Good morning everyone.

Playing with my hp prime, in solve app I tried with the example from the user manual,

EQ1: X-Y=-1
EQ2: (X^2)+(Y^2)=16

As you can see in the image, solve doesn´t works for this two equations on my HP Prime.

But, the behavior is correct for each of the equations alone.

However, and as it is logical, the behavior in the pc simulator and with android app, for the same operation is correct.

Please, can anyone check with the same equationes on your hp prime.

Thanks.