tomato upgrade E4200 "File contains an invalid header"

Hello,
I'm french and I'm really sorry in advance for my English.

Can you help me?

here is my problem: I upgraded my firmware on my Linksys E4200 with an incompatible versionof http://www.polarcloud.com/tomato file found -> tomato-K26USB-1.28.9054MIPSR2-beta-vpn3.6. trx

Now I is accessible only by Wireless in my web interface and not so local cable more opportunities to connect to internet.

I try many things without success
- With a firmware upgrade E4200 - error "File contains an invalid header"
- Several reset and still the same problem.

I've read in other site that the problem comes from the header of the firmware that has the wrongversion of the router. (for the latter insert my router is not the right)

I am at my knowledge in this area
I hope many of you

I thank you in advance.