the below is my code in which m trying to calculate tax amount ana it is showing nullreference exception......
Double Total1 = 0;
bool isTotal1Valid = false;
isTotal1Valid = Double.TryParse(TextBox154.Text, out Total1);
if (!string.IsNullOrEmpty(TextBox154.Text) && !isTotal1Valid)
{
// this is the case when user enterted a wrong value in the box
// you can show you user a message that price in in valid here
ErrorLabel.Text = "Please enter valid Tax Total, it must be numeric";
return;
}
...
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