Posted By:
Frank WakefieldDave,
They're telling you correctly. It is not real, send it back.
Stephen's suggestion is sound. If you can befriend a collector where you live who has some Cracker Jack cards. Once you actually see them, and feel them, then you'll be much better able to discern authenticity. Buying a low grade slabbed one and cracking him out might be a good way to do it.
A black light would help. Modern paper usually has brighteners in it, that fluoresces when illuminated with uv light. Paper after the late 40s usually glows purple, old paper doesn't. That CJ card you have would shine purple.
The 1914 cards are VERY thin, more like paper. They're actually a bit fragile. The 1915 cards are a bit thicker, and as mentioned above the reverse is flipped.