Hey alpal, Try looking at our troubleshooting page here. It sounds like you may have installed the blades incorrectly. If this is not the case, perhaps the blades are worn out, in which case you'll need to purchase a new blade. Hope this helps.
Hey again Alpal, Ninja Kitchen System Pulse Check out this page. This is the official Ninja website, and they carry replacement parts as well as useful extras such as the dough blade. Although a little pricey, they make excellent additions and will help should you have more problems with your blender. Ninja Kitchen System Pulse Troubleshooting
Hey Alpal, It sounds like you have not pushed down on the handle on the top of the device. Let's go through all the steps just to be certain though. (1) Start by inserting the blade into the bowl. (2) Next, throw all the fresh fruit you like into the bowl. (3) Follow by attaching the top and pushing down on the handle. (Handle will not lock down as this is your pulsing instrument) (4) Next, insert the bowl into the base, not worrying about locking. (5) Now, twist the bowl until you feel it lock. (6) When you're ready to PULSE, push down on the handle and watch her rip. Remember, the Ninja will do the work, but you have control over how long the pulse lasts. Ninja Kitchen System Pulse Troubleshooting