LR4 has a longstanding bug where it can no longer edit RAW files in Photoshop CS6. Various dead-end and fruitless suggestions have not fixed or solved this. These include complete operating system and LR4 and CS6 re-intsalls etc etc.
Most (including me) appear to be using a work-around where a copy is made of the Photoshop CS6 executable and slightly renaming it. this is then plugged into LR4 as a third-party editor. A far from convenient or professional affair!
Why does the Adobe Labs ADOBE RAW beta not update RAW in LR4 but only CS6?
What is the meaning of life?
Quote "Why does the Adobe Labs ADOBE RAW not update RAW in LR4 but only CS6."
Because Lightroom is a complete stand alone program and does not require the ACR Plugin which is designed to be used in PS CS and Photoshop Elements. Lightroom has the equivalent of the ACR Plugin built in to the program and when you update Lightroom the program is up to date and you do not have do anything further.
LR 4.4RC is the equivalent of ACR 7.4RC in PS CS6.
Lightroom does not even require you to have any other Adobe Products installed on your system for it to function.
The situation where some users are having problems with the "edit in PS CS6" functionality is discussed in many threads in this forum and maybe if you discribe exactly what you have been experiencing you may get some advice from one of the helpful users from the forum.
LR4 has the raw code built-in, the camera-raw plug-in on Adobe Labs is only a plug-in for Photoshop, but if you have ACR 7.4 RC and LR 4.4 RC both will have the same raw capabilities. Of course this probably has nothing to do with your original issue.