My file generator does not work after building with py2app

from Tkinter import *
from decimal import *
import re
import os

class Application(Frame):
  
    def __init__(self, parent):
        Frame.__init__(self, parent)   
         
        self.parent = parent
        self.grid()
        self.create_widgets()

    def create_widgets(self):
        """ Create widgets to get file name, size and type. """
        # create instruction label
        Label(self,
              text = "Enter file size and name"
              ).grid(row = 0, column = 1, columnspan = 2, sticky = W)

        # create a label and text entry for the size of a file
        Label(self,
              text = "File size: "
              ).grid(row = 1, column = 0, sticky = E)
        self.calc_ent = Entry(self, width=12)
        self.calc_ent.grid(row = 1, column = 1, sticky = W)

        # create a label and text entry for the name of a file
        Label(self,
              text = "File name: "
              ).grid(row = 2, column = 0, sticky = E)
        self.type_ent = Entry(self, width=12)
        self.type_ent.grid(row = 2, column = 1, sticky = W)


        # create a label File extension
        Label(self,
              text = "File extension:"
              ).grid(row = 4, column = 1, sticky = W)

        # create variable for single, extension
        self.option = StringVar()
        self.option.set(".txt")

        # create radio buttons, extension
        options = [".txt",".pdf", ".xml",".zip"]
        row = 5
        for ending in options:
            Radiobutton(self,
                        text = ending,
                        variable = self.option,
                        value = ending
                        ).grid(row = row, column = 1, sticky = W)
            row += 1

        # create variable for single, MB|MiB
        self.variable = StringVar()
        self.variable.set("MB")
        
        # create a label MB|MiB radio buttons
        Label(self,
              text = "MB or MiB:"
              ).grid(row = 4, column = 2, sticky = W)
        
        # create radio buttons, var
        variables = ["MB", "MiB"]
        row = 5
        for var in variables:
            Radiobutton(self,
                        text = var,
                        variable = self.variable,
                        value = var
                        ).grid(row = row, column = 2, sticky = W)
            row += 1

        # create a submit button
        Button(self,
               text = "Generate",
               command = self.create
               ).grid(row = 9, column = 1, sticky = W)

        self.message_txt = Text(self, width = 45, height = 2, wrap = WORD)
        self.message_txt.grid(row = 10, column = 0, columnspan = 4)

    def create(self):
        """ Assign variables based on user input. """
        # get values from the GUI
        size = self.calc_ent.get()
        name = self.type_ent.get()
        var = self.variable.get()
        opt = self.option.get()

        #check if size is not a string with a regular expression
        check = re.compile('\d+(\.\d+)?')
        if check.match(size) == None:
            message="Please enter a float (9.2) or an integer (3). Strings are not allowed."

        else:
            size=Decimal(size)

            if name=="":
                name="untitled"
                
            name+=opt
            directory = "output/test_files/"
            d = os.path.dirname(directory)
            if not os.path.exists(directory):
                os.makedirs(directory)

            name=directory+name
            check = os.path.abspath(name)
            
            #the magic
            if var=="MiB":
                with open(name,"wb") as output:
                    output.truncate(size * 1024 * 1024)
            else:
                var="MB"
                with open(name, "wb") as output:
                    output.truncate(size * 1000 * 1000)
                    
            message=name,size,var, check

        self.message_txt.delete(0.0, END)
        self.message_txt.insert(0.0, message)
        
# main
root = Tk()
root.title("File creator (c) David Baak")
app = Application(root)
root.mainloop()