error when activating a script with formsubmit

The following is the email I received when I failed to complete the form for the first time.

Your script, Query and Procedures Form, has not been executed correctly. Here is a summary of the errors. To configure the triggers for the script or change the configuration to receive future error notifications, click here.

The document Query and procedures form uses the script.

I'm getting this error:

  

Start: 10/18/17 12:34 Function: showQuestionNumber Message from   error: FormApp.getUi () can not be used from this context. (line 5,   "Code" file) Activation: formSubmit End: 10/18/17 12:34   Sincerely,

     

Google Apps Script

The code of the script is very simple:

function showQuestionNumber() {

      var questionnumber=5

      FormApp.getUi().alert('Su consulta tramitará con el número:    '+ questionnumber)
    }

I thank you for helping me solve this problem. regards Salvador