Missing Top and bottom skins?

[slybunda]

Hi all, im not sure what iv done here but one print i did worked fine but i dont have the gcode for the print that turned out ok (the middle blue one in the photo attached). Every one iv printed so far is like the green ones on the sides of the pic, they are missing the skin on them.iv tried different slicers, the good one was from wiibuilder, iv tried cura too and same issue.Printer is a weefun tina2. i dont get why/how i got 1 good print and not sure what iv changed either infill wise or something to end up with the odd prints im getting now. anyone got any ideas where i should be looking? the thing im printing is here: https://www.printables.com/model/281...uper-slim-case

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