custom calculation

I'm bringing in a session variable named "mthCost" which is cost for the remainder of the month for a membership business. If I use a flat fee as a test only, it shows up, but what I'm trying to do is add nothing to the variable "mthCost" and just display it as additional cost. I made a custom calculation "$_SESSION['mthCost'] + 0" but the name of the custom calculation is not showing up in eCart merchandising rule "calculations at the bottom" for me to select it, so therefore nothing shows on the display in the browser. The trigger is set for if the "session variable mthCost has a value greater than 0".

thanks

Why are you adding 0 to the value of the session variable in this?

I'm not sure what steps you're taking to get to where you're at. Can you take some screen shots and post up the steps you're taking so I can be more clear on what you're doing?

The only reason I was adding zero was in the custom calculation I thought it needed some calculation instead of just "Session variable as the value by itself". No problem I deleted the zero but the question is still the same. There are two of your pages, the first has 8 "add to cart buttons" with a session variable named "mthCost". I just need your "display manager", 2nd page, to display the variable as a charge. The name of the charge is set up in your "charges tab" so it will display but the value of that charge (session['mthCost']) is what I need to display without any further calculations or anything except to display the variable as it is as a charge. The calculations has already been done when it gets to the "display manager" so I just need to display the dynamic data.

To be clear it's the calculation at the bottom of the merchandising rule where I'm confused. I have the trigger to be if the session variable has a value greater than zero and I thought at the bottom calculation there would be a place to set the value to the "custom calculation" I did on the "eCart calculation tab" or just to the value of the session variable but it is not. That is where I get lost using your display manager to just display my values.
thanks

You will not be able to add an additional display to the display manager using the Wizard. You will have to manually add this after creating the display. Just copy the code for one of the rows and make the correct modifications and insert it into the area you want. You can replace the value being displayed with the session variable.