Environment variable for package configuration

Hi, gurus,

Thanks for your kind attention.

I am having a problem with environment variable for my SSIS package configuration. The thing is I can find the variable within the package configuration collection, but I can not see it from the system environment variables. When I open up the package, it always gives me warning that the specified environment variable can not be found. Can any of you give me any advices for it? Do I have to restart the machine where my package is running on?

Thanks a lot in advance for your help and I am looking forward to hearing from you shortly.

Best regards,

Yours sincerely,