speak method api example on http://msdn.microsoft.com/en-us/library/ff512420.aspx for multiple words

Hi,

I am using the example at 

http://msdn.microsoft.com/en-us/library/ff512420.aspx

for the text to speak engine. The documentation on the page states

The php example works fine on my server as is, however when I change the text from

$inputStr = "Welcome";
to 
$inputStr = "Welcome Dave";
I get no audio response. Could you explain how I can make the example work with sentences.
Thanks
Dave