Honeybee+ sda result difference

Dear all,

I have done sda calculation with honeybee+ DC recipe.

As below screenshot shows, sDA from sDA component with a blind state is 67.759563.
To make a sDA result figure, I also calculated sDA manually with “hourly values” component.
Hourly illuminance value is exported with same analysis grid and blind state, then compare the results of each points with 300 lux and count the hours that larger than 300 lux. Through my calculation, the area of analysis points that meet sDA 300/50% is 68.5544% of total area.

Does anyone can help to explain why there is such difference?

best regards,