The fiscal sponsor must be a 501(c)(3) organization as recognized by the IRS. The fiscal sponsor cannot be an organization whose tax-exempt status is pending. The sponsored project must be able to qualify for exemption under section 501(c)(3), even if the project has no intention of ever applying for it.
Pressing the Ignore button on the listed invitation on the LinkedIn site is effectively a soft rejection. The message then moves to your Archived folder. You can later choose to open the message again and accept the request.
I never found it to be a particularly fruitful endevour but there's nothing wrong with sending a second message. Girls get flooded on these sites and occasionally they just don't see things in their inbox. If after a second message you don't get a response just move on, it starts to get weird if you send a third one. In general though you have to have pretty thick skin as a guy if you do online dating, it's best just to move on if you don't get a response. Views.