OPC server 2012 cannot connect to Labview 2012 most of the times?

[Ola_A]

Hello, once in  a while I need to set up a new PC with the following, and try to get the OPC-server and Labview 2012 to talk to each other:

• Labview runtime 2012
• OPC server 2012
• DSC runtime 2012 (needed purely for licensing reasons, to get OPC running)
• Siemens PLC

My setup is that in OPC servers configuration I write the tags connecting the actual database adress on the PLC with a name accessible as shared variable. For example a tag with name "FF17.PLC1.Failure_bits.TI506_F" connecting to DB301.DBX55.1

In the labview project I deploy the library "OPC-Library" with OPC i/o-server "PLC1".

And then magically I can access the OPC tag in Labview code with adress like

ni.var.psp://localhost/OPC-Library/OPC1/FF17/PLC1/Failure_bits/TI506_F

But most of the time this does not work, and I never understand why! I reinstall the OPC2012/DSC 2012, etc. and in the end I often get it to work. But have no idea what I do wrong really. Is is naming, different version of Labview/OPC/DSC? Phase of the moon?

What is clear is that when I look in Distrisbuted system manager I can see my "OPC-library" with i/o server "OPC1". When it works I also have all folders with tags like "PLC1/Failure_bits". When not working I see only folder "NI OPC Client Status". See screenshots.

I just had a working installation, made a few changes to OPC tags and the Labview code. Compiled for LV2012. And bang, it does not work!
Reverting to old working exe and OPC file also does not work anymore. So clearly I am missing something here.

Can you help me out?