R Shiny(selectizeInput): object "choices" not found

I want to begin by saying that I am new at this. This code was working before, but now it doesn't run anymore. It gives me 'Error : object 'choices' not found' I have tried supplying it with rownames(z$genres),

• z is my data
• genres contains list of variables that I am trying to retrieve.

Any help is appreciated. Thank you in advance!

ui.R

conditionalPanel("sideBarMenu == 'CoordPlot",

                       selectizeInput("genre", "Genre", choices, 
                                      selected = choices[1])
      )

server.R

observe({
 output$barPlot <- renderPlot({
             z %>% filter(genres == input$genre) %>%  group_by(genres, newname2)%>%summarise(value = mean(values)) %>% ggplot(aes(x = newname2, y=value, fill = newname2)) + geom_bar(stat= "identity", width = 1, show.legend = FALSE) + labs(x = "Genre") +  coord_polar() 
   })
)