You’re running into the “double hop” problem, as described in “Secrets of PowerShell Remoting.”
Your credential delegates when you remote to SRV_A. However, once there, your credential cannot (by default) be delegated further. So SRV_A cannot access non-local resources.
The ebook Secrets of PowerShell Remoting describes this in more detail and offers solutions, which usually requires enabling additional authentication mechanisms and setting up multiple-hop delegation.