TimeUUID makes me crazy

[cbert...@libero.it]

I am getting crazy using TimeUUID in cassandra via Java. I've read the FAQ but 
it didn't help.
Can I use a TimeUUID as ROW identifier? (if converted to string)

I have a CF like this and SCF like these:

<ColumnFamily Name="Opecs" CompareWith="TimeUUIDType"/>
TIMEUUID OPECID (ROW) {
             phone: 123
             address: street xyz
}

<ColumnFamily Name="UserOpecs" ColumnType="Super" CompareWith="TimeUUIDType" 
CompareSubcolumnsWith="BytesType" />
String USERID (ROW) {
            TIMEUUID OPECID (SuperColumnName)  {
                                collection of columns;
             }
}

In one situation the TimeUUID is a ROW identifier while in another is the 
SuperColumn name. I get many "UUID must be a 16 byte" when I try to read a data 
that did not give any exception during his save.

at a Time T0 this one works: mutator.writeColumns(UuidHelper.timeUuidFromBytes
(OpecID).toString(), opecfamily, notNull); // (notnull contains a list of 
columns also opecstatus)

Immediately after this one raise an exception: selector.getColumnFromRow
(UuidHelper.timeUuidFromBytes(OpecID).toString(), opecfamily, "opecstatus", 
ConsistencyLevel.ONE)

I hope that someone help me understanding it ...