[Grammar] neither / every

[lille82]

Neither calculator worked properly.
Every calculator worked properly.

According to the solutions of the test only the second one is correct. Could you please help me on this?

Thanks a lot.

 

[5jj]

Neither calculator worked properly.
Every calculator worked properly.

Both are possible. More context might make one unacceptable.

 

[lille82]

Thank you. Yes, it would be easier to decide which one to choose if we knew that they have 2 or more calculators, but that is all in that example.