ContainerOverrides parameter

Hi,
I am using Constant JSON text to define the parameter for my Batch target.
I am having problem overriding the vcpus for the target job. I am aware the parameter naming should be in camel case but I having problem overriding the cpus.

For example, I want to override the vcpus to 6, but below will run the batch job but fail to override the vcpus.
{ "ContainerOverrides": { "VCpus" : 6, "Memory" : 2000, "Command": ["run_job.sh"]}}

Thanks in advance.