Hi Hilary and welcome to GoY. This plant survives fine in shade or semi shade and is not fussed as to whether the soil is acid or alkaline but does like it to be well drained, and to be kept moist. If you had it in a sunny area in your garden lack of moisture could have been the problem. The composts you have planted it into in the containers are possibly too rich for it. You don't say how long you've had the plant but in general plants don't like being constantly moved. I'd put it back in your garden and leave it alone for a while.

Type sarcococca in to the search box (Top right) it will come up with members experiences of growing this shrub. You may be able to work out what you need to do from the discussions engendered by the members plants. I was advised to give mine Epsom salts but I have not done it yet. I will wait until March or April.

Needs loamy, well drained but moist conditions in partial shade. That means it doesn't like boggy, poorly drained conditions, but does like soil which, though it drains, doesn't dry out completely. You could splash out on some John Innes No. 2 compost, repot, ensuring the drainage holes are working, stand in a shady spot (not dark, dappled shade best) and make sure its kept regularly watered to see if the one you have revives.