Time appending error

[parvkpr]

My specification is Always(dist & cgap). where dist is the predicate d > 10 and cgap is the predicate d<30. When I try to calculate robustness for the following trace, It fails to do so and gives a time appending error.

Trace: {'dist': (0.0, 20.0989990234375), (1.0, 20.06622314453125), (2.0, 20.0333251953125), (3.0, 20.02685546875), (4.0, 20.0), 'cgap': (0.0, 20.0989990234375), (1.0, 20.06622314453125), (2.0, 20.0333251953125), (3.0, 20.02685546875), (4.0, 20.0)}

error: ValueError: Trying to append a Sample timestamped at or before the Signal end_time,i.e., time is not strictly monotonically increasing.Current end_time is 4.0, given Sample is (4.0, 10.0).