Subtitles not loaded in Windows media player version 12

I’ve been searching the internet for days now looking for answers about the problem I am encountering with my Windows Media Player Version 12. All I want to do is play an .mp4 with subtitles but unfortunately it will not load the subtitles. I tried to install the K-Lite codec pack with the ffdshow, Haali, etc. but it still doesn’t work.
I never encountered this issue when I am using Windows Media Player Classic, I have the subtitles and all but I since I integrated my WMP version 12 as an active-x control in a program I really need to use it over the Classic one.
I hope somebody can enlighten me how to solve this problem.
