Can I work RSA1 tocde in multiple clients ( e.q 200,210 etc ) in same SID  of BI, as I'm  getting error while do it in 210 client. - error  "you can work only in client 200"

Hi,When my customer login system or do something in system, he will see apopup window which list some "Express document" for him to confirm. Hecan also find those information in "Business Workplace"---"Inbox". I'mnot familiar with workflow, he don't ...