HL7 validation with "dmr-z" is not work as expected

Hi,

My customer is implementing HL7 validation using EnsLib.HL7.Util.Validator.Validate in an HL7 production.
They set validation spec "dmr-z" because they want to allow unrecognized Z-segments and verify the presence of required fields.
Despite using "-z", Z-segments are not allowed and the following error occurs:
<Ens> ErrGeneral: Cannot validate segment schemas without a category.Unable to validate segment 8: ZPR.
Aside to that, when the verification spec is “dm-z”, the Z-segment is allowed as expected.
Can 't "r" and "-z" be used together? 
Is there any other way to implement both validations?