Multi color marking not working as expected to be

[smidhunraj]

Here is my full code https://github.com/smidhunraj/calendar I am trying to mark dates with 2 different colors for absent and present,When i load the calander no marking is shown. But if I move from month march to april and then may.aprils 29 th day marked is shown and if i navigate back i can see the dates as marked.Why is it behaving like that,My php code is here

https://github.com/smidhunraj/php-code.

Please help me.