pro tools express + windows 7 midi keyboard out!!

[FMviolin]

Hello,

i'm running with windows 7 , protools express 10 ,and my keyboard is roland ep5
Since i have by protools express. at first time this keyboard was recognized with usb midi sport , then without explication , no more !...so i 've connected
directly with midi cable , and it was working fine.
But since one month, midi is working but i can't work with my keyboard! midi thru is on , i've read many forum but no solution!! help! i don't understand!?..

Thank's!