Asterisk MYSQL problem

hello my friends, im a real beginner in asterisk and i really need help … my problem is when i run in my dialplan a command like this

exten=>123,1,System(mysql -u root -p5533 -e “SELECT * FROM tablename” mydb > text.txt )

it works just fine, i get all the fields outputed in the text.txt file

but when i do this query instead:
“INSERT INTO tablename (fname,lname) VALUES (‘Mark’,‘Gates’)”

it doesnt work :S my database does not get updated … i tried the escape character but i could be using it wrong … any suggestions???