Required Field Validator Error Message

I have a row in the grid which has a dropdown and a required field validator in each cell.
Initially all the required field validators are set Enabled=false. 
if(any dropdown in row selected)
{
all requiredfieldvalidator to be enabled.
}
else
{
no requiredfieldvalidator to be enabled.
}

 I am setting all the requiredfield validator as enabled or disabled as per the above rule. But I am unable to control the error message from the server side. It takes an extra click on the page to display the error message. is there a way to hide or show the error message from the server side itself.

Please Advice.