EMDK v2.6 - RFID3Sample5 not working?

Hello. I have to create an applöication which will read some basic informations from RIFD tags. This must be done in VB.NET. (Destination OS: Windows Mobile 6.5) I installed the Motorola EMDP for .NET v2.6 and checked the samples. The one that's useful is VB_RFID3Sample5. Unfortunatley it doesn't do anything. I can start reading as often as I like but it wont find my tag(s). That's kind of suprising since the sample application which was shipped with the MC3190-Z and nearly looks the same as RFID3Sample5 finds them immediately. Do I have to edit setting or something like that to make RFID3Sample5 work for me? Or does someone have a small working sample? Christian