RNA is a bit trickier to work with than DNA, due to its inherent instability and how prevalent RNases are (which are harder to inactivate than most enzymes). Is this your first time working with RNA? Do you have any controls you can run on your gel, or samples to include alongside the next RNA isolation? Best of luck!
when you work with RNA you must keep that in your mind that RNA is a decomposable molecule. you must wearing gloves during the experiment, cleaning your bench and etc. and one of the most important stage, when you work on RNA, is homogenization and for this step, you can use a homogenizer or you can use liquid nitrogen and Syringe. I think you have a problem at this stage
As the previous posters have highlighted, RNA is a very fragile entity. One of the biggest threats to RNA integrity is RNA'ses. They're everywhere. Wipe down all surfaces with RN'ase ZAP (or equivalent), make sure you're using RN'ase-free water (which you can purchase, or treat distilled water with DEPC). All of your reagents should be made with RN'ase-free water too, including downstream reagents such as PCR primers. You should also use tubes which are nuclease-free too. Eppendorf and other manufacturers make these.
Filter tips are an essential item - all sorts of contaminants end up in the barrel of a pipette. I would actually use a dedicated set of pipettes for RNA work which don't get used for anything else.
Never vortex your RNA unless you have a low sheer-force vortex.
How do you store your RNA? It is at it's most stable when stored at -80C (-20C is ok for a short time but not long-term storage).