Gridview Rowdatabound Event

Question

i have a grid bind on the pageload having a rowdata bound event and rowcommand event 

in a updatepanel. i have to change the color of the row according to the condition. on pageload rowdatabound event fire but does not reflect the UI but when i click on the button it reflects the UI also. so my question why the UI not reflect at the time of pageload even the event fire at the time of pageload