There may be more that one reason for this error coming up...
(1). since you have specified the column names in the query, check whether you have not missed out any column which is set to not null.
(2).The second reason could be that the datatype of the column and the datatype of the data does not match. So you need to convert it to the respective format before executing the query..
since i could not access the image (because of the restriction on our network) can you post the entire query that you are using.
i fixed the problem with that..but i can't insert this
INSERT INTO eras
( name , peasants , food , mana , infantry , cavalry , siege , naval , wizards , homes , mines , academies , barracks , mage towers , farms , towers , o_infantry, d_infantry, o_cavalry, d_cavalry, o_siege, d_siege, o_naval, d_naval) VALUES
('Dark' ,'Villagers' ,'Grains' ,'Mana' ,'Pikemen' ,'Cavalry' ,'Archers' ,'Galleons' ,'Wizards' ,'Huts' ,'Mines' ,'Academies','Keeps' ,'Mage Towers' ,'Farms' ,'Towers' , 1 , 2 , 3 , 2 , 7 , 5 , 7 , 6 ),
('Mystical','Peasants','Grains','Mana' ,'Swordsmen','Heavy Cavalry' ,'Bowmen' ,'Battleships' ,'Sorcerers' ,'Houses','Gold Mines','Military Academies','Keeps','Mage Towers' ,'Plantations' ,'Sentry Towers' , 2 , 1 , 2 , 6 , 5 , 3 , 6 , 8 ),
('Imperial' ,'Citizens','Grains','Mana','Long Swordsmen' ,'Cataphract','Crossbowmen','Juggernauts','Spellcasters ','Houses','Gold Mines','Imperial Academies','Keeps','Mage Towers','Imperial Plantations','Guard Towers', 1 , 2 , 5 , 2 , 6 , 3 , 7 , 7 );
http://img78.imageshack.us/img78/1299/mysql1sw5.jpg