Error in sql server with a trigger (I want to display a customize message, when the user left a blank field or null) How can I do?

Question

How I display a customize message(with a trigger)when a user left a blank field? I want to the stop the insert statament if the user left  the status field in blank. I create a trigger but now I can't enter a row, i used an instead trigger
too but doesn't work. I want to display a customize message when the user left the
status field in blank or null. 
 I have the following code:
CREATE TRIGGER [dbo].[BLANKFIELD] 
ON [dbo].[Status] 
FOR INSERT 
AS 
BEGIN 
IF (SELECT COUNT(*) FROM inserted WHERE Status IS NULL) =1
 PRINT 'Please Fill the Status  field is required'
Rollback;
END 

Answer 1

I agree with other comments that you should do this with specifying that the column is NOT NULL to prevent it from being NULL and a constraint if you don't want it to be blank (spaces or the empty string - note that the empty string is not the same thing
as NULL).
But for completeness, the reason your trigger does not ever allow you to enter a row is the code
IF (SELECT COUNT(*) FROM inserted WHERE Status IS NULL) =1
PRINT 'Please Fill the Status field is required'
Rollback;
Since you don't have a begin/end block after IF, the only conditionally executed statement is the one immediately following the IF (that is the PRINT).  So the Rollback is always executed whether or not the IF is true and so all updates are rejected.
So if you were to do this in a trigger you could do something like the following
CREATE TRIGGER [dbo].[BLANKFIELD]
ON [dbo].[Status]
FOR INSERT
AS
BEGIN
IF EXISTS(SELECT * FROM inserted WHERE Status IS NULL)
BEGIN
PRINT 'Please Fill the Status field is required';
Rollback;
END
END
(As José noted, there can be more than one row in the inserted pseudo table, so you don't want to test whether the COUNT = 1, instead just whether one or more rows exist where the Status  is null.  If you want to prevent Status is NULL, or all
spaces, or the empty string, then your IF statement would be
IF EXISTS(SELECT * FROM inserted WHERE ISNULL(Status, '') = '')
Tom