On a IA64 machine running SLES10 SP1 I (EVMS 2.5.5) had the following problem:
A disk with a resiserFS filesystem was converted to a EVMS Volume. Then it was converted back to a compatibility volume.
When trying to convert it back to a EVMS Volume again, the manager failed, because it found no filesystem to shrink.
The workaround was to add a filesystem to the compatibility volume ("mkfs"), and then the conversion would work (evms). Ugly, isn't it?