Timebar/Seek Buttons are disabled in Exoplayer for some .mkv files and hevc video files

It works for some mkv files perfectly but for some mkv files it does not show scrubber on time bar and when i try to seek video programmatically it starts from beginning
here is my code
```
simplexo=ExoPlayer.Builder(this,DefaultRenderersFactory(this)).build()
val datasource=DefaultDataSourceFactory(this,Util.getUserAgent(this,"app"))
concatenate=ConcatenatingMediaSource()

val mediasource=ProgressiveMediaSource.Factory(datasource).createMediaSource(Uri.parse(ok.get(position.toInt()).path)) concatenate.addMediaSource(mediasource)

playerview.setPlayer(simplexo)
simplexo.prepare(concatenate)

simplexo.seekTo(position.toInt(),C.TIME_UNSET)
simplexo.setPlayWhenReady(true)
```