Refuting reports that he has signed Amitabh Bachchan and Shah Rukh Khan for his next venture,R. Balki said,I have just started writing the script and will decide on the cast only after its completion. I have no knowledge about the source of these stories. R. Balki has previously worked with Bachchan in Cheeni Kum and Paa and with SRK for a short film. Balki,however,refused to divulge details about the story and prefers to talk about it only after he completes the script.