Unable to print S&D Invoices

HI Gurus,

I have created few Fixed Price invoices which have also been approved. When i am trying to print them using ZINVPRINT it shows an error "No data available for your entries".

Also in VF03 the status of the invoice shows as BLOCKED. Is that the reason why i am unable to print the invoice? If yes, why is it showing blocked and what to do in this case?

Please help.

Thanks!