Php Error in code something to do with parameters i think

Error is :
Fatal error: Call to a member function add() on a non-object in C:\Users\Ian\Documents\College\BSHSS\BSHSS4\server2go\htdocs\projectBookstore\phpModelerExtHopefully.php on line 149
piece of code below:

function addStatements($sub,$pre,$lit){
$statement1 = new Statement(new Resource("http://www.w3.org/Home/Lassila"),
new Resource("http://description.org/schema/Description"),
new Literal("Lassilas persönliche Homepage "));
addS($statement1);
}

function addS($state1){
$statement2add = $state1;
$model->add($statement2add);//error here just when it goes to add to rdf model
}

i get the error just when i go to add..
basically im trying to add statements to an rdf model so i declare and define statement1....pass it to addS function ....rename it......then try add it and get above error

any help Much appreciated!

Ian

 

if i am to take all code out of functions and use as below it works BUT i need it in functions as im adding many statements

$statement1 = new Statement(new Resource("http://www.w3.org/Home/Lassila"),
new Resource("http://description.org/schema/Description"),
new Literal("Lassila's personal Homepage", "en"));

$model->add($statement1);