Can anyone help with loading issues when button is clicked?

Hi everyone, I am having a little bit of trouble with a GUI button. I set the GUI to my script called UIAssistant which allows me to indicate which page is to be shown. I am trying to show a page called CardsReward, but for some reason Unity is causing the game to break without any errors.

I have included a picture for you to see what is happening.

My button script, which I am using the default button script from the engine, is set to UI and calls the UIAssistant.ShowPage and has the string attached as CardsReward. As far as I know, the engine should detect the page and display it when the button is clicked, but instead the game breaks.

I am calling the CardsReward page right after the WinPopup page by clicking on the button that says Next. I have included my script for the images to show them on the CardsReward page.

Can anyone let me know what I am doing wrong?