code

when do you want to check it?

on opening of a form or closing of a form or inserting a record,etc?

more info on what you are trying to do will help alot with the answer.

there is a property on the field called NOTBLANK - you can set that to yes,

But if the user never enters that field the message will not be triggered.

So I would search he forum for "Mandatory Fields" you will find many posts.

You can set every field you want mandatory to "not blank"=yes
once the field is filled it will always give you an error message if you try to "clear it".

as I said if the field is passed over then "not blank" does not help. you need to check in another way.
as I said searching for "mandatory" or "not blank" you will find many posts.

a good way is also described here:
http://dynamicsuser.net/forums/t/23883.aspx

The error message is unclear to me.
that trigger isn't the one i'd use.

Basically the steps are Oninsert the field "blocked" is set to TRUE!

Onvalidate of the blocked field (when the person goes to UNCHECK it to make it active)
it then checks the fields you want to have mandatory using a simple testfield code.

David Singleton wrote:

Basically in the on validate trigger of the "blocked" field you add code like

Testfield('My Field 1");
Testfield('My Field 2");
Testfield('My Field 3");
 etc.

This way when you try to unblock the customer you won't be able to till you fill in themissing fields.