UDC not able to access from FastPath

Hello Folks, Users not able to access UDC application from fast path when they type UDC in fast path at the same time when they entered P0004A in Fast path they are able to access. Kindly help me to understand what kind of security applied for the same as when they are trying to access UDC application  from fast path they are getting pop up i.e you have not permission access UDC application. Thanks Ramsajeevan