Retirement tax questions

You say "If all of your net earnings go to elective deferrals, nothing remains to fund the employer contribution."

I have made my full $19,500 elective deferral and $6,500 over-50 contribution for a total of $26,000. These are the maximum allowable amounts. But based on my self-employment income, I should STILL have, by my calculation, about $15,000 in employer contributions available. I told the system that I have made $10,000 in employer contributions to the 401k and another $5000 to a SEP. That should leave about $500 to go to maximize my contributions. But the system is telling me that I have about $5000 to still to go to maximize, and it seems to be ignoring the employer match I've already made. There is something wrong..... :(