I have patched the game to latest Generations and installed up to Late Night expansion but everytime my Sims take a shower. They don't leave behind any dirty clothes on the floor. Am I doing something wrong here?

You need to have a laundry item in the house for this to happen- a laundry basket or washing machine, perhaps. Do you have either of those?

OMG!!! Thank you so much Simsample for your switft response!!!!

I would never have known until you informed me. Gosh, I felt so stupid until I read your reply. I always thought that i should only start buying the washing machine only when my sims start leaving their laundry all over the place. I had the mentality of that "problem must first exist before the solution can be introduced".

Again much thanks for taking the time and being the first to reply.