Mob spawner delay remains at zero

I don't get it.

You placed a pig spawner and it doesn't spawn pigs (what else) ?
You set the delay tag to any non zero value but it remains at zero ?

My spawner, once i've placed it, doesn't spawn pig. So i check the NBT tag delay of the spawner and i've seen zero value, i think it's not normal.

I still don't get it.

Please answer my questions from above.

Using the /give 52 command to give yourself a spawner without modifying it will only spawn pigs. By default it does spawn pigs, so I assume you've modified it.
If you want to use the custom spawner feature, place the spawner in the world and use MCEdit with the SetSpawnerProperties filter. A tutorial is available at http://www.youtube.com/watch?v=rOHnWS8pdSg.

I've just do /give 52, obtain the mob spawner, place it.As it not spawned pigs, i've gone to check the NBT tag, by using NBTexplorer, which correspond to the spawner's delay, but i've don't modify it. Normally, I expect this tag's value is not equal to zero. delay seems don't increase.

NBT tags of the item does not affect the block you place, you must place the block and modify the individual block itself.

I've just looked the NBT tag delay of the block, not the item. But i realized spawner works in normal world, and not in the superflat world. I've tested two presets, redstone ready and desert, so i can't say if the problem is from the biome (biome desert, right) or from the superflat world.

Canu Quentin: Works on my superflat world. Pigs need grass to spawn, so deserts will prevent pigs from spawning, are you sure your world has grass in it?

I didn't know that pig can't spawn on sand. With redstone ready preset, there aren't grass, so i understand pig can't spawning. But when i tried to do a spawner who spawn four differents item, i doesn't work too. So i imagined that spawner doesn't work at all on the desert biome.