bulb with brown spot
 

Hi, i have a burrageara nelly isler who have a bulb with a brown spot at top. Is a bulb who had a flower spike. At beginning start with leaves, brown tips,i cut them, but still spread , when leaf from top of the bulb become all brown, the bulb start to become brown at top and now is spread to bottom. The bulb have good roots, bark is new, don't stay in sun, i water when bark is close to dry and i don't sprinkle the leaves..the bulb have a new growth, is small 3-4mm but still green. What happens? Is normal or is ill bulb? To cut and to sacrifice the new growth? Please help me!

Plecase excuse my bad english. :-)

bulbs whas shriveled when i bought the plant

I would remove that bulb right away as it could be brown rot and that spreads to the other bulbs if not removed. If you have Isopropyl alcohol, dip a cotton ball in it and then gently wipe down the other growth to disinfect it. Don't get the alcohol on the roots as it will dry them out too much.
Good luck! Nelly Isler is one of my favorites!

Here is a nice guide that I really like:
Orchid Pests, Orchid Diseases

thank you. i will remove the bulb. still i don't know what i did wrong...why the bulb rot.. :(
usual rot start from bottom to top, not like in my situation..