ASP.NET button does not fire on the first click

I've already digged in the topic from a lot of websites and cant find a solution. Whenever i click the button, it does not fire on the first click, but on the second. I have tried several things, but nothing seems to work.

Any help is appreciated.

Here is the code of the button:

<asp:Button ID="btnPeliculas" runat="server" Text="ABM peliculas" CssClass="btn-primary text-center" Height="50px" Width="200px" Font-Bold="True" Font-Size="Medium" OnClick="btnPeliculas_click" />

the onClick function is the following:

protected void btnPeliculas_click(object sender, EventArgs e)
        {
                Server.Transfer("frmwPeliculas.aspx");
        }