There is no component setting in the answer file that needs to be added for BitLocker to run. The device driver for the TPM chip has to be running. Please make sure you see the TPM driver under Security Feature in Device manager. Also, go to Control Panel->Administrative Tools->Services, and check the settings for BitLocker Drive Encryption Service. Make sure it is running, and set to auto start. If the services is disabled for some reason, the you can add a Pass7 sync command to start teh service using sc.exe.
Do you see BitLocker Drive Encryption in Control Panel?
From a command prompt, if you run manage-dbe -on c: -skipthardwaretest, does the encryption process start?
If you are deploying the image to multiple systems, each system has to run BitLocker since the TPM chip is unique for each system. BitLocker has to be disabled in the master image, and using a Pass7 sync command, you can kick of the encryption using manage-dbe.exe utility. Sometimes BitLocker kicks off automatically for some systems, but that doesn't sound like what is happening here.
Regards,
Sean Liming