Anemones are tough to keep alive, no matter what you read/hear (except for those darn aptasias). Carpet anemones are especially challenging.
Sounds like you have lighting problems. What size tank do you have and how much lighting do you have? If you don't have it least 4-5 watts per gallon of lighting, you don't have enough.
You also need a stable tank for them with pristine water parameters (ZERO ammona, nitrate and nitrite, pH of 8.3 AT ALL TIMES, Sg 1.025, dKH 10-12 and Ca >350). for long-term health of your anemones.
Many believe that they have good systems because their anemones live for months to a year or more when in fact, they are dying right off the bat. Anemones can/will slowly eat themselves over weeks to months in order to survive in an inadequate environment. Regular feedings prolong this but the end result (death) is inevitable. Many that you see in stores already have started that due to poor shipping conditions, etc. Captive bred anemones are far better in this regards in that they are usually always healthier by the time they get to the store.
Give me your tank parameters and equipment and we can go from there. Perhaps there is something that you are overlooking that is killing your anemones (like a heater leaching heavy metals). You also could just be getting bad anemones from your store (see above comment).
