When I send image from LR to PSCC for editing the filtergallery filter is grayed out. But if I send the image to Desk top and then to PSCC, it is not. What I am doing wrong that it makes it grayed out?
The filter gallery is greyed out, when a condition is given, that does make use of the filter gallery impossible. That happens if the image is 16 bits/Channel (Image->Mode). With 8 bits/channel the gallery is accessible. You export 16 bits to PS and 8 bits to the desktop.
Change your image to 8bits or change your preferences and the Gallery is accessible. I wouldn't change the preferences, because you will loose your editing accuracy. If you want using the gallery however, the 16bits is overkill.