Trigger not triggering - sql-server

Question

I've got two tables as per diagram below
here is sql script for USERS TABLES
USE [NewUser]
GO
/****** Object: Table [dbo].[USERS] Script Date: 15/12/2014 18:26:05 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[USERS](
[FirstName] [varchar](50) NULL,
[SureName] [varchar](50) NULL,
[DOB] [date] NULL,
[USID] [numeric](18, 0) IDENTITY(1,1) NOT NULL,
CONSTRAINT [PK_USERS] PRIMARY KEY CLUSTERED
(
[USID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
And for ADDRESSES TABLE
USE [NewUser]
GO
/****** Object: Table [dbo].[ADDRESSES] Script Date: 15/12/2014 18:26:35 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[ADDRESSES](
[AID] [int] IDENTITY(1,1) NOT NULL,
[USID] [numeric](18, 0) NULL,
[AddressLine1] [varchar](50) NULL,
[AddressLine2] [varchar](50) NULL,
[PostCode] [varchar](50) NULL,
CONSTRAINT [PK_ADDRESSES] PRIMARY KEY CLUSTERED
(
[AID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF
GO
ALTER TABLE [dbo].[ADDRESSES] WITH CHECK ADD CONSTRAINT [FK_ADDRESSES_USERS]
FOREIGN KEY([USID])
REFERENCES [dbo].[USERS] ([USID])
ON UPDATE CASCADE
ON DELETE SET NULL
GO
ALTER TABLE [dbo].[ADDRESSES] CHECK CONSTRAINT [FK_ADDRESSES_USERS]
GO
After that I have created a TRIGGER using
USE [NewUser]
GO
/****** Object: Trigger [dbo].[autoupdate] Script Date: 15/12/2014 18:33:09 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER TRIGGER [dbo].[autoupdate]
ON [dbo].[USERS]
AFTER INSERT, DELETE, UPDATE
AS
BEGIN
SET NOCOUNT ON;
DECLARE #TEMPID INT
SET #TEMPID = (SELECT USID FROM INSERTED)
UPDATE ADDRESSES
SET USID = #TEMPID
END
The purpose of the TRIGGER is to insert UID automatically on the second table as soon as a new row is added or updated in first table.
But its not doing what I was expecting it to do.
Screenshots
USERS TABLE
ADDRESSES TABLE
USID from table USERS and AID from table ADDRESSES both has "Is Identity Set to YESS"

Answer 1

I'm assuming this is SQL Server, not MySql - please remove the conflicting RDBMS tag.
With triggers, you'll need to handle set data - the INSERTED and DELETED pseudocolumns are tables, not single rows.
Also, assuming that you aren't going to be updating the PK [USID] on Users, you won't need to handle an UPDATE in the trigger, just INSERT and DELETE, and it looks like you've already decided to handle deletes on user with ON DELETE SET NULL, which will set the USID foreign key to NULL in Addresses.
So this leaves INSERT - I'm guessing here you only want to insert an empty address for new users?:
ALTER TRIGGER [dbo].[autoupdate]
ON [dbo].[USERS]
AFTER INSERT
AS
BEGIN
SET NOCOUNT ON;
INSERT INTO ADDRESSES(USID)
SELECT USID FROM INSERTED i
WHERE NOT EXISTS (SELECT 1 FROM ADDRESSES a WHERE a.USID = i.USID)
AND i.USID IS NOT NULL;
END

Answer 2

In order for your trigger to do anything the way you've designed it, you need to have records already in the Addresses table. Once a record exists, it's USID will be updated when a record is updated or inserted in the Users table.