Warning: htmlentities() expects parameter 2 to be long - UTF8

[Savera]

Hi
I am trying to sanitize UTF8 string and now I am getting this error
Warning: htmlentities() expects parameter 2 to be long, string given in s\www\dict\includes\functions.php on line 7

I have used
   return htmlentities(mysql_real_escape_string($string);

Now I am not sure is it because of this htmlentities or some other part ?