[SalesForce] Attach a VisualForce Page, Rendered As PDF to a Record

That's because try{} catch{} block didn't solved your problem, it just catch exception and handle it...

About code, try:

PageReference thePage = Page./*your page*/;
        thePage.setRedirect(false);
        thePage.getParameters().put(/*your atribute*/ , /*value of atribute*/);
        blob body = null;
        if (!Test.isRunningTest()){
            body = thePage.getContentAsPDF(); 
        }
        // It is here for testing purposes - as you cant call ".getContentAsPDF()" methode in test
        else{
            body = Blob.valueof('Some random String');
        }     
        attachment pdf = new attachment();
        pdf.name = /*name of your attachment*/;
        pdf.body = body;
        pdf.ParentId = /*Id of parent object */;
        pdf.isPrivate = false;

        insert pdf;

On the attaching the PDF part of your question, you can connect your button to a controller method as described in e.g. Call Apex Class From A Custom Button.

To generate the PDF and attach it you can use the getContentAsPDF method and insert the Attachment:

global class MyClass {
    webservice static void attachPdf(Id customObjectId) {
        PageReference pr = Page.YourPageName;
        // Add parameters (if any) passed from the custom button or queried locally
        pr.getParameters().put('id', ...);
        insert new Attachment(
                ParentId = customObjectId,
                Name = 'Whatever Name You Want',
                Body = pr.getContentAsPDF(),
                ContentType = 'application/pdf'
                );
    }
}