Something JLE said is the first thing I thought about (ip helper-addresses). If you can get access to login to the switch, find the relevant documentation online for your switch and verify if the VLAN has an ip helper-address configured.
On our ProCurves, we could check like this:
show ip helper-addressor we could configure like this:
config vlan <vlan_number> ip helper-address <IP_of_your_DHCP_server> write mem end