Kevin, I am running version 3.99. This is the details of the error.
	 
	AssemblyVersion: 5.6.2
	PortalID: 0
	PortalName: Toners Outlet
	UserID: 1
	UserName: host
	ActiveTabID: 64
	ActiveTabName: HP
	RawURL: /Store/HP/tabid/64/ctl/Cart/mid/417/Default.aspx
	AbsoluteURL: /Default.aspx
	AbsoluteURLReferrer: http://tonersoutlet.com/Store/HP/tabid/64/ctl/Cart/mid/417/Default.aspx
	UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.16) Gecko/20110319 Firefox/3.6.16 GTB7.1
	DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
	ExceptionGUID: d8d3ef8a-52f6-4f19-ab08-ca3d14bae6a7
	InnerException: Object reference not set to an instance of an object.
	FileName:
	FileLineNumber: 0
	FileColumnNumber: 0
	Method: Smith.DNN.Modules.BuyNow.Cart.IsRestrictedState
	StackTrace:
	Message: DotNetNuke.Services.Exceptions.PageLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at Smith.DNN.Modules.BuyNow.Cart.IsRestrictedState() at Smith.DNN.Modules.BuyNow.Cart.btnApply_Click(Object sender, EventArgs e) at System.Web.UI.WebControls.ImageButton.OnClick(ImageClickEventArgs e) at System.Web.UI.WebControls.ImageButton.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.ImageButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---
	Source:
	Server Name: DS000787