J river media center 16 sansa clip and flac

I have a new 4 GB clip and my flac files on Jriver media center 16 but Im unable to load the flac files onto the clip through jriver?

I get a files not supported type message.  I can however drag the folders with flac files into the music folder on the clip and it works.  I just dont understand why it wont work through jriver.  If anyone has any experience with this I would love the insight.

Thanks

After I transferred the flac files to the folder directly I thought things were A OK.

Today at work The clip just crashed while playing now it wont even turn on.

I didn't rockbox the clip.  I never put it into msc mode when I transfer ed the files but after doing some reading it sounds like the sansa's can be pretty fowled up by moisture.  It was my first time using it and I was on a stair mill machine.  I may have got some sweat on it and that's that.  I have tried the whole holding down the power button thing to no avail.  I will return it and see what happens with the next one.  I was under the impression the sansa would support flac though and I would not need to rockbox it?

Thanks for the reply

Well no worries now.  Returned the defective player to find out there were no more.  It was on sale for 30 bucks but without a deal im opening up my options again.

I'm not sure what to try I liked the size and simplicity of it but it didn't sound that great to me but I may have not transferred my music right either.  Kinda up in the air.  Put a post out for opinions.  Without some great sale Im looking at everything.

Thanks