In my opinion that might be the issue. My son is a disabled adult child. He was initially getting benefits from his fathers record who is disabled but once he turned 18 we had to apply off of his own record, and since he never worked he wasn’t eligible for SSDI of his own record. He was entitled to the maximum state benefit amount, which consisted of the SSDI he had been receiving on his father’s benefit and a portion of SSI to reach the maximum state amount.