Invoice Numbers

[ScrltOTara]

Hi:

 

I have set my invoice numbers as such so I can differentiate between hosting invoices and other company invoices:

 

Sequential Invoice Number Format Enter the format for the paid invoice numbers eg. WHMCS2007-{NUMBER} - I put in the box: HST-{NUMBER}

 

However, it still is generating only numbered invoices. For example, last night it was supposed to generate: HST-12003 and instead it was just 12003.

 

Am I missing a setting?

 

Thanks.