Having trouble with 7 mth old doxie?

He is very rough with my other dachshund always growling and my other dog is constantly running away, is this okay? i don't know if its just how he plays but hes extremely aggressive. We've been trying to get him ociated with other dogs but he bark expressively and just freaks, help i don't know what to do we've been doing training with him but hes just crazy, i need the dog whisperer.