Unknown column in where clause

Hello,

Error message is:
Unknown column 'expireds.Site_Address' in 'where clause'

Am getting this error when executing the following procedure, can't figure out where I'm messing up. DB Mgr (SQL Mgr 2010) is finding the columns (once I type in the table name, a list of columns pops up, and I'm able to select the columns by clicking on them):

INSERT IGNORE INTO expireds (Parcel_Number, Comments)
SELECT `Oc Phn`, `Showing Instructions`
FROM actives
WHERE actives.`Address`= expireds.`Site_Address`
;

Tables:

CREATE TABLE `actives` (
`Prcl#` varchar(20) NOT NULL,
`Address` varchar(30) NOT NULL,
`City` varchar(20) default NULL,
`Zip` varchar(10) default NULL,
`Status` varchar(5) default NULL,
`LA Full Name` varchar(30) default NULL,
`LA Phn` varchar(16) default NULL,
`Oc Phn` varchar(16) default NULL,
`Showing Instructions` varchar(255) default NULL,
PRIMARY KEY (`Address`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;


CREATE TABLE `expireds` (
`ID` int(11) NOT NULL auto_increment,
`First_Owner_First_Name` varchar(30) default '0',
`First_Owner_Last_Name` varchar(30) default '0',
`Second_Owner_First_Name` varchar(30) default '0',
`Second_Owner_Last_Name` varchar(30) default '0',
`MLS#` varchar(30) default '0',
`Status` varchar(15) default '0',
`OMD` date default NULL,
`FollowUpDate` date default NULL,
`date_last_checked` date default NULL,
`Site_Address` varchar(30) default '0',
`Site_Unit` varchar(10) default '0',
`Site_City` varchar(20) default '0',
`Site_State` varchar(2) default '0',
`Site_Zip` varchar(6) default '0',
`Mail_Address` varchar(30) default '0',
`Mail_Unit` varchar(10) default '0',
`Mail_City` varchar(20) default '0',
`Mail_State` varchar(2) default '0',
`Mail_Zip` varchar(6) default '0',
`Parcel_Number` varchar(20) default '0',
`E-mail` varchar(40) default NULL,
`Comments` varchar(9999) default '0',
`Met` tinyint(1) default '0',
`MetDate` datetime default NULL,
`Phone1` varchar(15) default '0',
`Phone2` varchar(15) default '0',
`Phone3` varchar(15) default '0',
`Phone4` varchar(15) default '0',
`Phone5` varchar(15) default '0',
`Phone6` varchar(15) default '0',
`Phone7` varchar(15) default '0',
`Phone8` varchar(15) default '0',
`Phone9` varchar(15) default '0',
`Phone10` varchar(15) default '0',
`Phone11` varchar(15) default '0',
`Phone12` varchar(15) default '0',
`Phone13` varchar(15) default '0',
`Phone14` varchar(15) default '0',
`Phone15` varchar(15) default '0',
`DNC` tinyint(1) default NULL,
PRIMARY KEY (`ID`),
UNIQUE KEY `Site_Address` (`Site_Address`),
UNIQUE KEY `Site_Address_2` (`Site_Address`),
UNIQUE KEY `Site_Address_3` (`Site_Address`),
UNIQUE KEY `Site_Address_4` (`Site_Address`),
UNIQUE KEY `Site_Address_5` (`Site_Address`),
UNIQUE KEY `Site_Address_6` (`Site_Address`),
UNIQUE KEY `E-mail` (`E-mail`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Thank you in advance for any and all help!!!!!