To specify the device boot program using the /BootProgram parameter, you must also use the /Force parameter. The /BootProgram ...

To specify the device boot program using the /BootProgram parameter, you must also use the /Force parameter.  The /BootProgram parameter should only be used with versions of WDS prior to Windows Server 2008 R2. To change the per-device PXE prompt policy, use the /PxePromptPolicy option instead of manually specifying the boot program.