Testifying in court: Subpoena says tomorrow, but call today said Wednesday. Confused. Advice?

I have to testify in court for the first time ever this week, and I've been in contact with the District Attorney's Investigator for a couple of weeks now. The date on the subpoena says I am to appear at 8:45 AM on Tuesday, April 5, 2011. Late today while I was busy working on stuff I got a phone call from the Investigator, and he said "Hi, this is Bladiblah just calling to let you know we will (tone: infact) need you to come in on Wednesday at 8:45 AM". The way that he said it was like "we do still need you to come in", rather than sounding like there had been a change to the court time, so it was a quick call that was basically me just saying "ok, see you then". But like I said, on my subpoena the date says tomorrow morning. I looked on the county court website, which has a search feature, but it didn't have anything added for Wednesday, and the court case I have to show up for isn't listed at all. I wish I had caught the difference in date before now (10:50 at night). Tomorrow's a really busy day, so I really need to know which date I am to show up on. Any advice / opinions?