Try removing the ".Date" bit:
txtFromDate.Text = DateTime.Now.ToString("dd/MM/yyyy");
And then use DateTime.Parse or DateTime.TryParse (preferred) to convert back from a string to a DateTime.
BTW: Don't keep using DateTime.Now, it is re-generated each time you do that.
Get into the habit of reading it once, as it can eliminate strange errors later on - the time can change between sucessive reads.
DateTime now = DateTime.Now;
txtFromDate.Text = now.ToString("dd/MM/yyyy");
txtToDate.Text = now.ToString("dd/MM/yyyy");