Thanks mateia !!! It's working now.

 In my code problem is order of .css class style and  .cs apply order.

For any one else, order should be always like following  -  

.cs

this.UltraWebGrid1.DisplayLayout.RowStyleDefault.CssClass = "RowStyle";
this.UltraWebGrid1.DisplayLayout.RowAlternateStyleDefault.CssClass = "RowAltStyle";
this.UltraWebGrid1.DisplayLayout.HeaderStyleDefault.CssClass = "HeaderStyle";

and in .css

.RowStyle{background-color:Blue;}
.RowAltStyle{background-color:White;}
.HeaderStyle{background-color:Green;}

Hey Guys,

I have found an alternate ways but not sure whether I am correct or not ...

I have commented the below line

UltraWebGrid1.DisplayLayout.RowStyleDefault.CssClass = "cssOddRow";

and added the following

UltraWebGrid1.DisplayLayout.FrameStyle.CssClass = "cssOddRow";

Now it applies Header style, Alternate row style correctly and for rest of the frame it will take cssOddRow style.

But I am not sure whether it's a correct way ....

Thanks shareeef !!!

Setting OptimizeCSSClassNamesOutput property to false prevents odd rows to take header style.This code resolves my 50% problem.

But Issues are still there. I have to apply different CSS for odd and even row. Following is the code :

UltraWebGrid1.DisplayLayout.RowStyleDefault.CssClass = "cssOddRow";

UltraWbGrid1.DisplayLayout.RowAlternateStyleDefault.CssClass = "cssEvenRow";

The above code by default take cssOddRow style for all rows.

Any solution ?