InsertUI with selectInput does not show list of values from a DF

[danimaiams]

Hi people.

How can I use insertUI with a "selectInput" to show a list of values to choose?

Like:

UI:
actionButton("plot", "Plotar!"),

SERVER

   ...

   df
    
    tabela_saida = df
    
    valor_le = df$LE
    
    valor_tr = df$TR
    
    relacao_ts = (valor_le/valor_tr)
    
    valor_grau = df$Grau

     observeEvent(input$plot, {
      
      insertUI(
        selector = "#plot",
        where = "afterEnd",
        ui = selectInput(
          "grau",
          label = "Grau:",
          choices = valor_grau,
          selected = 1
        )
      )
    })
    
  })   
  

This insertUI will update the value of "choises" in the "valor_grau = df$Grau" values, but it always shows it blank, like the image.

Ps.: My DF is with no problem

If someone can save me...