GRE name change

Hi

I have a problem with GRE name.
I have registered with

First name : Manoj
Middle Initial: K
Last Name : Reddy

But in my passport it's like

First Name : Manoj
Middle Name: Reddy
Last Name : Kamana

i Have entered middle name in place of last name in GRE account and most important i have registered for the test :(

will the ETS change my last name if a send them scanned copy of my passport or should i cancel my test :(


Thanks in advance.