I have been trying to make libraries for RNAseq. Originally I used RNA isolated from cell lines using RNeasy mini kit from Qiagen. The libraries were prepared using the KAPA biosystems kit by Roche. Everything worked fine. Then we extracted RNA from human frozen breast tissue using Allprep DNA/RNA/protein kit by Qiagen. The quality of RNA was good and the concentrations were very high. I made the appropriate dilutions per the KAPA biosystems kit for the library prep, performed the lengthy procedure, several times; however, every time when I QC the libraries either the library peak is absent but the adapter dimer peak is present or the library peak is present and looks normal but there is also a prominent adapter dimer peak. I have repeated this several times but cannot figure out what the problem could be. How do I lose RNA or the developed libraries? I carefully follow the kit's instructions and have checked all the critical steps multiple times, but the issue persists. Please see one of the BioA results file below and help me out. Thank you.