How to check if a file exists from a https website

I am facing problem while checking if file exists in a https website. My below code works for http websites but it does not work for https websites.
Full file path needs to passed like https://image.shutterstock.com/image-photo/colorful-hot-air-balloons-flying-260nw-1033306540.jpg

Public Function URLExists(ByVal url As String) As Boolean
    Dim webRequest As System.Net.WebRequest = System.Net.WebRequest.Create(url)
    webRequest.Method = "HEAD"
    Try
        Dim response As System.Net.HttpWebResponse = CType(webRequest.GetResponse, System.Net.HttpWebResponse)
        If (response.StatusCode.ToString = "OK") Then
            Return True
        End If
        Return False
    Catch
        Return False
    End Try
End Function

What I have tried:

I have tried to pass below file paths to test it. You can use your own and check it.

HTTPS
https://image.shutterstock.com/image-photo/colorful-hot-air-balloons-flying-260nw-1033306540.jpg

HTTP:
http://zprajnandgaon.gov.in/img/map.png

For Example:

Label1.Text = URLExists("http://zprajnandgaon.gov.in/img/map.png")

Returns True

Label1.Text = URLExists("https://image.shutterstock.com/image-photo/colorful-hot-air-balloons-flying-260nw-1033306540.jpg")

Returns False even if the file exists

Please help me.

Tags: C#, Visual Basic, ASP.NET