RentTrack reports your payments on or around the 15th of the month. It may take a few months of payments to see a change.
RentTrack displays the VantageScore v3 score, which considers rental information in its algorithm. Not all credit scores (including FICO scores before FICO '09) consider rental information and therefore may not factor in rent payments appropriately. In addition, there can be many changes month over month in all the factors that make up your credit score (see the FAQ titled "Understanding Your Credit Score"), so it is difficult to predict how one factor might impact it alone.
It may be helpful to request your latest credit report from http://www.annualcreditreport.com and see what might be affecting your credit. RentTrack is not a credit counselor and therefore cannot advise you on what might be affecting your credit.
While there are multiple factors that influence credit scores, the continued reporting of on-time rental payments can be beneficial according to the latest studies by major credit bureaus: