AN unemployed man who threatened a restaurant worker over a claimed injury sustained in a football match was ordered to attend a drug addiction treatment centre yesterday for extorting ''compensation''. So Ma-fook, 24, was convicted after trial in the District Court on two counts of robbery and a count of blackmail. He had pleaded not guilty before Judge Tyler to all the charges. A report read out in court confirmed So was addicted to drugs and gambling. The prosecution said on July 16 last year So approached Tsang Chui-man, 22, and two of his colleagues at a fast food restaurant in Tai Po and demanded cash. After being assaulted Mr Tsang handed over $100 cash and some gold ornaments to So. So then took Mr Tsang to a bank and forced him to withdraw $5,000. The following morning So returned to the restaurant and told Mr Tsang's superior that Mr Tsang had caused him to suffer a leg injury during a football match. So demanded $20,000 from Mr Tsang as medical fees for his injury. But Mr Tsang, who denied the accusation, refused to pay. So left a pager number and was arrested by police six days later.