date of birth validation

i have one field in design page as follows;

Date of Birth textbox1(calendar image)

i want to validate date of birth date should be greater than the todays date and more than the todays date.

for that i write the code as follows;

DateTime DOB = Convert.ToDateTime(FromDate.ToString());

if(FromDate.SelectedDateValue > DateTime.Now)
{
Label6.Text = ("you have not born yet");
}

i try the above code when i run i show the error message as follows;

Operator '>' cannot be applied to operands of type 'string' and 'System.DateTime.

for my above code please correct my code and reply.

thanks,please help me.