Can't open modals from code behind

[gabryk91]

I saw this is a common problem, I am used to open them from codebehind using an hidden button and a small piece of jscript, like this:

<button type="button" style="display: none;" id="btnModal" class="btn btn-primary btn-lg" data-toggle="modal" data-target="#modalRegole">Launch demo modal</button>

<script type="text/javascript">
        function ShowModal() {
            $("#btnModal").click();
        }
    </script>

and this code behind call: ClientScript.RegisterStartupScript(Me.GetType(), "alert", "ShowModal();", True)

This works on all my other bootstrap project except the one where i'm using sb admin template.
I need to edit what the modal will show by changing its components texts and visibility and I don't know how to do this without using code behind. So I don't want to open them using attributes data-toggle and data-target.

Any help? Thanks