CRS can be difficult to sex. With that said, I doubt that you received all males with your last shipment. How many shrimp did you receive? I am new to CRS/CBS and when I received my order I looked at them and thought I had no females (I was comparing them to my RCS females). I asked the seller if he sent me any females and he told me that he was certain that I had females. Three weeks later (four weeks after putting them in my tank) I noticed that I had a berried female CBS.
What makes you think that they are all males? Are they not breeding for you? If so, what are the water params?
Well, I'm not sure if there are any females or not, but I haven't noticed any saddles on any of the shrimp. The shrimp are in soft water (pH6.8 KH3 GH3). I have cherries in there breeding, so maybe they're just young. I guess I'll wait them out a bit longer to see what happens.
FWIW I haven't seen saddles on my CRS yet either. I came home late one night after working 17 hours and I checked my shrimp tanks. I was really surprised and did a double take because I thought I was seeing things. When I looked more carefully I saw that my female CBS was indeed carrying eggs. The eggs are black too! How funny. RCS are incredibly easy to breed and that's an understatement. Caridina species are more difficult to breed (with some exceptions) than neocaridina species. Just because your RCS are breeding doesn't mean that your CRS will be breeding. They need soft acidc water. You have that so maybe in 4-6 weeks you will see some eggs depending on how large your shrimp are.