New Post: Problems using Pay With Paypal option

I'm trying to setup NBStore on a site for a client, but I keep running into an error when trying to checkout with Paypal.

1. The Pay with Paypal image does not display
2. When I try and use the pay with paypal I get this exception:
   

Error: NB_Store_Checkout is currently unavailable. DotNetNuke.Services.Exceptions.ModuleLoadException: Object reference not set to an instance of an object. ---> System.NullReferenceException: Object reference not set to an instance of an object. at NEvoWeb.Modules.NB_Store.Gateway.GatewayPayPal.StringListReplace(String value, String searchfor, String replacewith) at NEvoWeb.Modules.NB_Store.Gateway.GatewayPayPal.PayPalEncode(String value) at NEvoWeb.Modules.NB_Store.Gateway.GatewayPayPal.SetBankRemotePost(Int32 PortalID, Int32 OrderID, String Lang, HttpRequest Request) at NEvoWeb.Modules.NB_Store.GatewayWrapper.SetBankRemotePost(Int32 PortalID, Int32 OrderID, String Lang, HttpRequest Request) at NEvoWeb.Modules.NB_Store.CheckOut.GatewayRedirect() at NEvoWeb.Modules.NB_Store.CheckOut.Page_Load(Object sender, EventArgs e) --- End of inner exception stack trace ---

Please help. Thanks.