dhcp leasing problem

I have a dhcp server which connects around 200 nodes. Before, there were no problems with regards to dhcp but when we start to create an exclusion and use those IPs as static on some nodes which cannot lease an IP from the server, other nodes which can lease before start to have paroblem. Right now almost 70% of our nodes uses static IP which is taken from the exclusions.

Can anybody tell me how to resolve this problem? I know that there is something wrong with our DHCP server.