Command Block outputs on even if the arguments are not the right ones

Expected Behaviour:
The command block outputs off when the arguments are not right.

Actual Behaviour:
Outputs on even if the arguments of the command are not right. Happens with

 /testfor @p[score_<objective>=number] 

Steps to Reproduce:
1-Make an objective.
2-Set it to display (Optional but helpful)
3-Set a command block testing for

 /testfor @p[score_<objective>=1] 

4-Update the command block with a redstone pulse.

Note that the output stays on even and you have 0 points. score_<objective>=number is supposed to work only with a specific number