Nero Vision 4 problem

Hi, My Nero vision 4 causing problems in importing the vedio
files.( I am using Nero 7 Ultra edition)
when I click browse and add media files and selects the Vedio TS, Nero Vision says unable to insert Vedio TS IFO and Vedio TS BUF files resulting in failure to make movie or DVD.
Please let me know the solution.