What RDA are you using, and on what mod? You say it reads 0.00 ohms, so I'm guessing you have a regulated mod of some type, and it is this that's reading 0. Most mods like that will say "no atomizer" or "check atomizer" when you try to fire it if it isn't making contact at all, but not all of them. They may read 0 at rest, when you aren't hitting the fire button.
One of three things is wrong: the topper isn't making contact with the mod; you have a dead short at the coil; or the mod is bricked. Do you have an ohmmeter? (IMHO, nobody should be building coils without an ohmmeter, but others disagree.) If so, check it on that. If it still reads 0.00, the topper is shorted. Take off the top cap. If that fixes it, your coil is touching the cap and shorting. If not, the coil itself is shorted between the posts. If it reads 0 on the mod, but has acceptable resistance in the ohmmeter, it isn't making contact, or the mod is fried. If the mod works with a different topper, it isn't fried.
It would probably help if you could post some pics.