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What i cant upload a big audio files( like more than 12Mb)?

I have a problem of uploading big audios like of more than 12MB, i have tried many time to upload different big audio in different browser, but the back-office didnt complete the process, it doesnt event show the error that occured, when i use google chrome it shows the progress in percentage, it reaches 100%, and says "WAIT FOR DOMAIN.COM TO RESPOND"(browser’s message not SPIP’s) and in few seconds backend stops without displaying the audio, i have checked where SPIP stores audio(/public_html/IMG/mp3/) i didnt find it, i would like to know how i can fix this issue?
I use SPIP 3.0.11
thank you so much!