problem with appending translated subtitles to MKV

[Heliooos]

Hi,
I have one document which contains also English subtitles for the deaf - appended to the MKV. I extracted them into SRT (UTF-8) via MKVExtract GUI 1.5, translated them in my native language without changing file parameters like charset etc. Finally, I wanted to somehow replace the MKV subtitles (of if possible to have them both in the file).


[Attachment 5907 - Click to enlarge]

However, I am unable to get the subtitles there:

mkvmerge v4.5.0 ('Speed of Light') built on Feb  1 2011 02:10:32
'H:\DVD VIDEO\nove\BBC_Birds of Paradise_720p (1).mkv': Using the Matroska demultiplexer.
'H:\DVD VIDEO\nove\BBC_Birds of Paradise_720p.srt': Using the SRT subtitle reader.
'H:\DVD VIDEO\nove\BBC_Birds of Paradise_720p (1).mkv' track 1: Using the MPEG-4 part 10 (AVC) video output module.
'H:\DVD VIDEO\nove\BBC_Birds of Paradise_720p (1).mkv' track 2: Using the AC3 output module.
'H:\DVD VIDEO\nove\BBC_Birds of Paradise_720p.srt' track 0: Using the text subtitle output module.
Error: The track number 0 from the file 'H:\DVD VIDEO\nove\BBC_Birds of Paradise_720p.srt' cannot be appended to the track number 2 from the file 'H:\DVD VIDEO\nove\BBC_Birds of Paradise_720p (1).mkv'. The formats do not match.

What I am doing wrong?

thanks