Fix a bug in my code

I'm using Canvas to let my users "design" an add that later is transformed into an image to be displayed on my website. In this design, the users can add their logo. I'm using this funtion to add the logo to the canvas: function canvasLogo(){ var x = 70; var y = 70; // var width = 500; // var height = 500; var imageObj = new Image(); [login to view URL] = function() { var imageWidth = [login to view URL]; var imageHeight = [login to view URL]; if (imageHeight > imageWidth) { imageWidth = (imageWidth / imageHeight) * 490; imageHeight = 490; } else { imageHeight = (imageHeight / imageWidth) * 490; imageWidth = 490; } x = x + (500 - imageWidth) / 2; y = y + (500 - imageHeight) / 2; roundedImage(70, 70, 500, 500, 30, 0, 0, 30); [login to view URL](); [login to view URL] = "white"; [login to view URL](70, 70, 500, 500); [login to view URL](imageObj, x, y, imageWidth, imageHeight); [login to view URL]("Logo cargado"); }; [login to view URL] = [login to view URL]; } And then the users add other things like text and colors and finally when they click the button to create the add I use: function crearAnuncio(elm){ if($("#advanced-wizard").valid() && [login to view URL] > 0){ [login to view URL](); [login to view URL] = "z"; setTimeout(function(){ render(); [login to view URL](1*3,1*3); setTimeout(function(){ kanv = [login to view URL]([login to view URL]); var imgB = [login to view URL]("image/png"); var serialForm = $("#advanced-wizard").serialize(); var arguments = serialForm+"&file="+encodeURIComponent(imgB); deliver(arguments); [login to view URL]([login to view URL]); // Run paypal if(global.form.idMetodoPago==1){ [login to view URL]('paypal_process').submit(); } else { [login to view URL] = ''; deliver_site(arguments, "[login to view URL]"); window.location.href="[login to view URL]"+[login to view URL]; } [login to view URL](); }, 550); },150); } else { alert('Seleccione el método de pago '); } } To transform the canvas into a png which is then displayed on my site. The thing is that sometimes (haven't been able to replicate the error myself and the clients say it only happens "sometimes") their logo is not rendered in the final image (text and colors do). The space for the logo is just blank. The clients tell me that they could see their logo on the canvas before pressing the generate button. It doesn't appear to be related to operative system or browser since the same computer sometimes creates the add alright and sometimes without the logo. I thought it was my server so I changed and upgraded the hosting and it still happened. Any idea on what could be going wrong? Thank you.