Change status b2 to f1 while inside US, necessary proof of funds?

[tc1981]

Hello,

I visited US as a tourist 3 times for last couple of years. I have my US bank account with $20K savings for my study. I want to change the status from tourist B2 to student F1. Can I be my own sponsor to file I-539 and show my US bank statement? Every time I came to US I brought...

[idkn]

So.

My I 94 expired at 21 April 2016.
I applied for change of status 31 March 2016
Start date of my classes: 18 April 2016
I got denial letter 21 July 2016 with the date 18 July 2016

I got denied because according to them SEVIS start date of my classes is...