no sound when recording from external (comp) into 500 help

i just bought two rca cables and the 1/4 inch adaptors at one end so i can plug into the in port of my mpc and a dual mini jack to hook both the chords up to so i can plug them into my headphones jack on my computer so i can take samples from youtube ect.

but i plug them in and click record, and it says waiting input device and then i cant hear it and if i turn the rec gain up to maximum, i can barley hear it like i almost have to hold my breath barley hear it .also its only coming out of one earphone (in the mpc). so i switched it form stereo to mono L and the soudn came out of both, but it still says "waiting input" and none of the bars show up to say the mpc is even regestering sound, i recorded the track anyway and exported it back to my laptop in a .wav and i opend the file up in windows media player and it had no sound at all, just 2 minutes of silence. whats wrong? has this happened to anyone else? i also clicked the button in the back, the mic and the line one and neither one of those seemed to change. whats up with this???? its pretty frustrating.


any help would be appreciated

did i buy the wrong cords? i even asked the guy at the store what to buy and he told me how to hook it up and everything.

record it internally onto ur pc first into in pc recorder program / multi track software etc...

then once u got that saved on ur pc and u can see / hear the wav and know u got the sound,, then sample / load it into ur mpc

thanks complex, but actually, i think i got it, cuase i was sampling stuff off my ipod when i was out fishing away from town. i think the cables were just not fully connected cuase they were new and i didnt know if they were or not.

but ill keep your idea in mind too for when i dont have my mpc with me or something