Subset()

Hello,

I have a dataset containing Date Time, Air Temperature, PPFD, Sol
Temperature...
The first data are false so I would like to extract the other ones.
I've tried :

data1<-subset(data,DateTime>=as.POSIXct("2017-01-10

11:00:00",format="%Y-%m-%d
%H:%M:%S"),select=c(DateTime,PPFD_Avg,Air_Temp_Avg,RH_Avg,Soil_Temp_Avg))
But I still have 4 rows with data from 2017-01-10 10:00:00 to 2017-01-10
10:45:00 and I don't understand why.

Does anyone could help me please.

Thanks,

Elise LIKILIKI