Do they have any right to charge me with "Unlawful Consumption of Liquor by a Minor" with no present evidence?

I was at a college in Illinois visiting my sister. I went to a fraternity and could not find my way back to my sister's apartment. One guy I was hanging with at the fraternity asked me if I wanted to stay the night at his place. I graciously accepted and we went to sleep in the basement of his house. I was awoken in the morning by an older gentleman asking who I was. I told him that I came here with another guy last night who invited me to spend the night. I was asked to leave, so I did. However, there were police outside and the "homeowner" decided to press charges against me for Criminal Trespassing. Anyways, I went to court the other day and plead not guilty. The person pressing the charges against me was NOT present. The judge also said I had a charge of "Unlawful Consumption of Liquor by a Minor". I was never breathalysed or blood tested, so I don't know where they have this evidence. Shouldn't my charges for Criminal Trespassing be dismissed if the accuser is not present? Since I plead not guilty, the judge gave me another court date, without even hearing my story or reading the police report.