Here's some of the debugging info... does "fail" mean it simply didn't find a suitable result that round, or that there's some issue?
To stake a block, the hash of the output that is trying to stake must be lower than the target hash. In this case 38f... is less than 2d4d... (it's one character shorter) and so it wins the right to stake.
Then every 16 seconds you'll see your outputs trying to stake:
[STAKE] searching for staking opportunity:
2015-02-18 07:22:09 [STAKE] checking 18 output(s)
2015-02-18 07:22:09 [STAKE] check fe7c7692b2ca1969ed4fb431144f6a15815f2a57b3bda9bbf8fcb2f338af9d28:107 (4.00 CLAM)
2015-02-18 07:22:09
[STAKE] fail: hash 413d56c739eb1bf553a51d7f642fe66d094f931746e433b14cda85178224d7ce
[STAKE] > target 2d53118d2c00000000000000000000000000000000000000000000000000
2015-02-18 07:22:09 [STAKE] check fe7c7692b2ca1969ed4fb431144f6a15815f2a57b3bda9bbf8fcb2f338af9d28:125 (4.00 CLAM)
2015-02-18 07:22:09
[STAKE] fail: hash ccd1436cf112218abb68f704f1bfbd54f4b9206d3bc58dc76162af15a05e5266
[STAKE] > target 2d53118d2c00000000000000000000000000000000000000000000000000
I have 18 unspent outputs, but I've cut the log off after the first 2 failed to stake. In both cases the hash is much bigger than the target, and so those outputs didn't get to stake.