I create digiCardPass with updateTag column that is timestamp. 
I try: 

```
   $query1 = mysql_query("select MAX(updateTag) as updateTag from digiCardPass");
   $row1 = mysql_fetch_array($query1);
   $updateTag = $row1['updateTag'];
   error_log("max updateTag:",$updateTag,0);

```

But I cannot get this error in php\_error.log: 

> 
> [03-May-2013 12:46:06 Asia/Phnom\_Penh] PHP Notice: A non well formed
>  numeric value encountered in
>  /Applications/MAMP/htdocs/passesWebserver/createPass/index.php on line
>  42 [03-May-2013 12:46:06 Asia/Phnom\_Penh] max updateTag:
> 
> 
> 

```
   //line 42: error_log("max updateTag:",$updateTag,0);

```

How to solve this problem ?