Gerbil Owners Read please help:?

I have rats and it took several months to get one of my rats to behave with the other two. first though you need to get them to trust you. separate the Grey from the others. he may just be a loner. next sit in a same room with your other three and play with them. let them go to you dont try to go to them. after they are used to you try the grey. it may take a while but after you are trusted by all 4 introduce them back and supervise them. try adding sugar to the water to get them to drink more plus it will help rehydrate them