Okay that is the problem.
As I mentioned, there is no such thing as white ink for these machines.
It produces white areas in an image by not putting any toner in those spots, and assumes the use of white paper for a white background.
All of the toners are dark pigment type colors, meant for use on a white background. Using colored papers, especially a dark paper, will produce dark or off colors. There is no light ink, just as there is no white ink.
You may want to consider printing your project on white paper, then cutting/trimming and laying that on top of the blue card stock as a background.
Otherwise, for what you are wanting to do, your machine simply is not appropriate (and really no consumer grade machine is). You'd be looking at having to do screen printing or another type of transfer process for that.
Best regards, ***** ***** for the news,