Server Scripting fails under Frappe version 14

Hello, hopefully someone can help me out.

I am using Frappy version 14 under Linux.
Now I found the Server Scripting Option in the Build Workbench.
I used this Script to check if the Date is possible to use or not

import frappe
from frappe.model.document import Document

class Projekt(Document):
	def validate(self):
        	if self.startdatum and self.enddatum and self.startdatum > self.enddatum:
      		      frappe.throw("Startdatum muss vor Enddatum liegen")

If I want to Save a Project, I get the Error

import not found.

Does somebody have a good Suggestion ?
Thanks :wink: