Disability Insurance

I received a call from the disability office stating that I was not eligible for our states disability insurance. It's the one that I've paid into for 25 plus years and they're advising me that I cannot receive payments because I'm already receiving "sick pay" from my employer at my part-time rate. Living in California, we either pick up massive hours to compensate for the rent or mortgage and other necessities that we need to survive or have two jobs. I have the latter where as I am able to pick up large amounts of hours to where I am able to compensate my part time hours into full-time. So why won't they pay me? Because picking up hours is not my "customary work schedule"!! Heck, they should have told me that before going on disability. I would have upped my status, if possible, to full time and THEN taken disability. That would have made better sense. So it makes me think, why pay into a system when they can't help you, even with an appeal. What do all the other part-timers do in this situation? Just venting, thanks for listening!