Hey guys,<BR>I am developing a signup form on my site where users select from a dropdown based on a database table(manufacturers). If the value they are looking for is not in the dropdown I want to provide a textbox for them to specify their other manufacturers by writing them here.<BR><BR>What i want to know is how to validate these controls i.e If the selected value of the dropdown is null then look at the textbox and if that is null raise an error. I can do this through an if then stmt but want to find out if i can use conventional validation controls so the errors will appear in the same way as the rest of my form, as the response.write appears before all html in .net<BR><BR><BR><BR>