mysql stored function gives error (if - else)

I have a stored function wich won't execute well, but I don't know what I am doing wrong. I want to check if the key exists in the database.

• if so -> then update
• else -> create

---

Code won't format, why?:

BEGIN

IF EXISTS(SELECT MenuItemID FROM menuitem WHERE MenuItemID=_MenuItemID)
    BEGIN
    UPDATE menuitem SET MenuID=_MenuID,ParentMenuID=_ParentMenuID,PosIndex=_PosIndex,XamlFileID=_XamlFileID,CanExpand=_CanExpand WHERE MenuItemID=_MenuItemID;
    END
ELSE
    BEGIN
    INSERT INTO menuitem (MenuItemID,MenuID,ParentMenuID,PosIndex,XamlFileID,CanExpand) VALUES (_MenuIt5nuID,_ParentMenuID,_PosIndex,_XamlFileID,_CanExpand);
    END

RETURN ('success');

END