When you record a scenario, there are values corresponding to your input and selection. These values are most likely dynamic and based on the data at the time of recording or running the scenario. This means that on each playback of the recorded script, it plays back the exact same parameters and values. If a set of values needs to be dynamic, and you are playing them back as static content, this will cause problems, as the server is expecting a certain request with certain data to be sent.

To solve this, you most likely need to correlate some data and parameter values so that they are run dynamically. You will have to compare the requests recorded with the requests on playback to see what data is handled already dynamically, and what is statically the same. What is static might need to be handled through extraction and correlation.