Mermaids not transforming in water

Hmm, I was perhaps unclear, I meant that mermaids are NOT showing their tails in the water.  All the of the games premade mermaids are swimming like humans in clothes that aren't their swimwear at times.  In my old save from before my system was upgraded I played a custom mermaid, so I loaded it up to see if this was affecting my own played mermaids and it was not.  It may be that if I invited them to my household it might clear up whatever conflict is occuring with them, unfortunately thats not something I can do everytime this is a problem.  My current sim is dating Uku right now, but he still swims like a human and doesnt transform into his merself, just like the others.  I'll give a repair a try though, that may be all that is the problem, I wanted to see what anyone said first before wasting my time, in case it had something to do with the hard drive copy/origin doing something odd.  Thanks for your reply!