HI Mangesh,
Is TACACS is configured for the devices and are you using customize prompt to login to device.Is it happening for all the device or any specific types of devices ? Kindly share this to troubleshoot this issue.
Kindly make sure that you provided the correct credentials for the device into Ciscoworks like a normal user try to login to device.
You can verify your credentials that you had provided into DCR from Common Services > Device and Credentials > Click on Export tab and select the devices for which you want to cross check the credentials. You can also take packet capture while CiscoWorks trying to verify the credentals for the device.
Thanks,
Gaganjeet