In GuildBook 5.563, line 588 of gb2.lua, ViragDevTool:AddData(GUILDBOOK_GLOBAL, "GUILDBOOK_GLOBAL") should be commented out because that function doesn't exist (in that form) in ViragDevTool. You could also change it to ViragDevTool_AddData or ViragDevTool:Add but it appears that all the other debugging lines are commented out so that is probably the best option.