ST-Link Utility, Can not connect to target!

16:19:16 : Can not connect to target!
Please select "Connect Under Reset" mode from Target->Settings menu and try again.
If you're trying to connect to a low frequency application , please select a lower SWD Frequency mode from Target->Settings menu.
16:19:44 : No target connected
Hi this the error im facing when try to program using stlinkV2 on a custom board
Tried switching to powerdown mode also and also checked the connections of pcb
what could be the issue
