Can't add a Order Product to an Order

Hi,

I have CRM2016OL and i am trying to add a order product to the order. When I click the + sign on the order products subgrid i can select existing or write in. The objective is to select existing but i want the order product form to open up instead of giving me a list of order products. If select the + sign and then new...instead of the order product form opening up i have the price list items form open up.