I guess that is the penalty one has to pay using dislocated data type. The said return can be approximatively understood from the ordering of character code (0 as 0x30, 1 as 0x31, etc...) from left to right of descending significance. In any case, the filter is problematic and it does not conform with the relevant rfc.
Instead, try this before it becomes unmanageable (and has to be generated by code).
[tt]
(|(umhsSkelEffectiveDateS=02\2f10\2f2011)(umhsSkelEffectiveDateS=02\2f11\2f2011)(umhsSkelEffectiveDateS=02\2f12\2f2011)(umhsSkelEffectiveDateS=02\2f13\2f2011)(umhsSkelEffectiveDateS=02\2f14\2f2011)(umhsSkelEffectiveDateS=02\2f15\2f2011))
[/tt]