I'm working on a program and withen it i need to take a value from a textbox in one form to text box in another form

i wrote this code to do this

Code:
Public Class Form4
    Dim generator As New Random

        MaskedTextBox1.Text = generator.Next(Form3.MaskedTextBox1.Text)
        MaskedTextBox2.Text = generator.Next(1111111, 9999999)
i have two text box in form4

in the first one i need to take a value from3 randomally

in the second one i need to generate a random data ..


when i run the code i face a probem, the program tes me that there is an error;

Conversion from string " -" to type 'Integer' is not valid.


Can anybody plz tell me what's wrong ??

I linked the program with my database (access) by new source data