NAT issue

Hello all,
i’m trying to make next:
i have a rb1000 router with 4 interfaces, ether1 is on ip: 62.101.1.1/24 - ether2 is on ip: 87.250.1.1/30 - ether3 in on 109.105.1.1/30
which is connected with ether1 to cisco switch 2650. also i have a cisco router connected to the switch.
ether2 & ether3 are connected to the internet directly.
cisco router have users on network 192.168.200.0/21.
so i’m NATing 192.168.200.0/24 to 62.101.1.200
and 192.168.201.0/24 to 62.101.1.201, etc…

now when i NAT one of these networks for wxample 192.168.200.0/24 to 109.155.1.1.
225 X chain=dstnat action=dst-nat to-addresses=109.105.1.1 dst-address=192.168.200.0/24
226 X chain=srcnat action=src-nat to-addresses=109.105.1.1 src-address=192.168.200.0/24
It works for while, then the DHCP on CISCO can not give ip’s for PC’s from the network 192.168.200.0/24. - the allready connected user’s from earlier are working, but new users can’t get ip’s.

any one can help?

Thanks.