Seems the magic __call() function used with the overload extension is converting the name of the function called (the first argument of __call()) to lowercase.

Best summarized with a script;

<?php
class Test {
    function Test () {
        echo ('Test constructed<br />');
    }
    function __call($method,$args) {
        echo ( 'Method called: '.$method.'<br />' );
        switch ( $method ) {
            case 'testa':
                echo ('testa('.$args[0].') success<br />');
                break;
            case 'TestB':
                echo ('TestB('.$args[0].') success<br />');
                break;
            case 'TESTC':
                echo ('TESTC('.$args[0].') success<br />');
                break;
            default:
                echo ('Method unknown<br />');
                break;
        }
    }
}

overload('Test');

$o=new Test();
$o->testa(1);
$o->TestA(2);
$o->TESTA(3);
$o->testb(1);
$o->TestB(2);
$o->TESTB(3);
$o->testc(1);
$o->TestC(2);
$o->TESTC(3);
?>

Output of above script;

Test constructed
Method called: testa
testa(1) success
Method called: testa
testa(2) success
Method called: testa
testa(3) success
Method called: testb
Method unknown
Method called: testb
Method unknown
Method called: testb
Method unknown
Method called: testc
Method unknown
Method called: testc
Method unknown
Method called: testc
Method unknown