sapreste dirmi perchè scrivendo questa riga

html += onmouseout=" function (event) {alert(\'here I am\');}" onmouseover="function (event) {alert(\'he went thataway\');}">


ho il seguente errore?
Parse error: syntax error, unexpected T_FUNCTION in C:\Inetpub\wwwroot\ordini\vcl\dbgrids.order.inc.ph p on line 740