MSSQL and PHP

[donkey_ears]

Hi,

I have kind-of a problem. I've been working on a web service, which comunicates with a MSSQL server. The problem is that mssql functions don't seem to return a value 'FALSE' when an error occures. this only happens when I use them inside the function of the web service server php file, which creates it's own WSDL file. If i use the code in a simple php page it works ok.
here is some of the code:

class SQL {
    .....
  function SELECT($sql, $db) {
 	if(!($db_link = mssql_connect('MUHA','root','pseto')))
 	{
            ...same problem
 	}

  if(!($db_s = mssql_select_db($db, $db_link)))
  {
  	$return[0] = 'failed';
 	return new SOAP_Value('return','{urn:SQL}ArrayOfStrings',$return);
 }
 $return[0] = 'OK';
 return new SOAP_Value('return','{urn:SQL}ArrayOfStrings',$return);
    }
    .....
}
....

If I run this code with a database name that does not exist, the page freezes till a timeout occures, or some other strange stuf
The thing is, that if I use a mysql database and mysql_select_db() it works just fine.

Any ideas why this would be so??
Any body had the same problem??
Thank you