I am trying to perform relative quantification of telomere length using RT-PCR, with triplicates for each sample, including positive and negative controls. The results showed good Ct values for the samples and the positive control. However, the negative control showed a Ct value of 24.2, while the Ct values for the samples were all below 20.0. Notably, the melt curve did not show any peak for the negative control, while the samples displayed the expected melt curve. What could be the reason for this? What measures can I take to optimize my reaction so that the negative control is clear?