The way I understand it is you take your ranks in the skill then apply the ability modifier for the situation. Thus, if you're doing Gather Info and chatting some people up it's based off Charisma. If it's recalling knowledge, then it's Intelligence. The thing is, you only did your Int mod and didn't add Roy's ranks in Streetwise (Gather Info on the sheet. Guessing you didn't update it with the skill change?) to the check.