When is the last day to cash winning tickets for 2015?

I had a winning ticket from Santa Anita I made at Evangeline Downs on June 5th. I mailed them my ticket last week and I was told it could not be cashed because it was 90 days after the Santa Anita 2015 Spring Meet ended. Of course there is nothing written on the ticket or website with these rules.

My understanding is that you can still cash tickets till April 15th the following year. Am I right about this?

Thanks for your help