I had the Page Action Trigger working perfectly to add products to the Cart within an Iframe.
This is the Querystring I'm using: ?rvdspact=2&rvdsfpvqty=1&rvdsfpid=1&rvdsfpvid=5

Then I was trying different things and I setup a custom Template for the Product and noticed that made the Page Action Trigger stop working. Instead of going to the "Buy Now" or even just quietly adding the product it loads a page with the product and "Buy Now" and "Add to Cart" options. if I click either it works, but that doesn't really work from within an Iframe.

So, I assigned the template for that product back to the Blank option on top and it went back to working.

THEN, I assigned the same template to the products from the Template Configuration page, rather than the Product/Display page. Not sure what I thought that would accomplish, but it didn't help anything. The Page Action Trigger stopped working again. I tried unassigning that template, deleting the template, assigning a standard template then unassigning, everything I could think of and now if I use the Page Action Trigger I get an error page with this Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
DotNetNuke.UI.Containers.ActionBase.get_ActionRoot() +29
DotNetNuke.UI.Containers.ActionBase.Page_Load(Object sender, EventArgs e) +41

[ModuleLoadException: An error has occurred.]
DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(String FriendlyMessage, Control ctrl, Exception exc, Boolean DisplayErrorMessage) +373
DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(Control ctrl, Exception exc, Boolean DisplayErrorMessage) +184
DotNetNuke.Services.Exceptions.Exceptions.ProcessModuleLoadException(Control ctrl, Exception exc) +33
DotNetNuke.UI.Containers.ActionBase.Page_Load(Object sender, EventArgs e) +109
System.EventHandler.Invoke(Object sender, EventArgs e) +0
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +50
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Control.LoadRecursive() +141
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627

[PageLoadException: An error has occurred.]
DotNetNuke.Services.Exceptions.Exceptions.ProcessPageLoadException(Exception exc, String URL) +269
DotNetNuke.Framework.PageBase.OnError(EventArgs e) +394
System.Web.UI.Page.HandleError(Exception e) +84
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +6776
System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +242
System.Web.UI.Page.ProcessRequest() +80
System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) +21
System.Web.UI.Page.ProcessRequest(HttpContext context) +49
ASP.default_aspx.ProcessRequest(HttpContext context) +4
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +181
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

I did try clearing the cache several times during the process to see if that would help. Any other ideas what might get this Page Action Trigger working again?