The errors you are getting are telling you that the included file cannot be found in the location specified. So for the connection it is going to the parent directory of the current page and looking for the Connections folder then the connection file.
Based on the paths you have it seems that the page you are working with is in a sub directory of the site. You will need to ensure that the WA_eCart and Connections folder are in the root of the site if this page is in a sub directory.
When you have the paths to the files matched up correctly you will not get this error.