Error Will Not Print Or Raiserror

I am testing a simple stored proc below.
create procedure procpooh @val1 int, @val2 int as
insert into pooh (val1, val2)
values(@val1,@val2)
declare @error int
SELECT @error = @@ERROR
IF @error <> 0
BEGIN
print 'it failed'
RAISERROR(50020,16,1,@error)
end

When I run the proc and feed it the values it fails(that' what I expect)
because there is a field not being supplied which will not allow nulls.
However neither the print ' it failed ' or the raiserror work. I get the message below instead. Any ideas why the print or raiserror don't work?
Server: Msg 515, Level 16, State 2, Procedure trpooh, Line 11
Cannot insert the value NULL into column 'val3', table 'Chapter5DB.dbo.pooh2'; column does not allow nulls. INSERT fails.
The statement has been terminated.