ClassCastEception with ReadList

Hi,
I'm having trouble when reading some objects in List. Server is based on gxsimulator.
All attributes can be read alone, but when in list, I got:

class [B cannot be cast to class java.lang.Number ([B and java.lang.Number are in module java.base of loader 'bootstrap')
gurux.dlms.objects.GXDLMSDemandRegister.setValue(GXDLMSDemandRegister.java:578)
gurux.dlms.GXDLMSClient.updateValues(GXDLMSClient.java:1510)
cz.vutbr.client.reader.MyReader.readMyList(MyReader.java:839)

I know, that some values are null in this object, but when every attribute alone works just fine, list should work too.

I noticed that in some other cases, but always the object on server had some values as null.

When dubbugging, i found a value for index 9 (on line 578 in demandregister). EventValue was [7, -28, 12, 6, 7, 21, 56, 8, -1, -1, -60, 0], but for this, there should be only one number.

I have this object:
<GXDLMSDemandRegister>
<LN>1.5.32.27.0.255</LN>
<Access>111133333</Access>
<MethodAccess>00</MethodAccess>
<CurrentAverageValue Type="18">0</CurrentAverageValue>
<LastAverageValue></LastAverageValue>
<Scaler>1.000000</Scaler>
<Unit>0</Unit>
<Status Type="17">0</Status>
<CaptureTime>12/06/2020 21:56:08+01:00</CaptureTime>
<StartTimeCurrent>12/06/2020 21:56:08+01:00</StartTimeCurrent>
<Period>0</Period>
<NumberOfPeriods>0</NumberOfPeriods>
</GXDLMSDemandRegister>

I guess best solution is to make better xml for server with all values specified...