d600 thats a lappy right ? most like case or cpu fan you've replaced, some lappys only have the one fan for all of it.
you replaced the old one cos it wasn't spinning ?
new one doesn't work...hmmm
1. is it under warrenty ? call the number.
2. double check the connector to the mobo is in properly and the right way round (usually you can only connect them the right way, if you try the wrong way it won't fit)
If that ain;t it, possibly the connector on the mobo is history..man that would be bad news.
Get to a PC repair shop have them check the fan out and the connector on your lappy for a current.
If you're happy to do it and can get your hands on a volt meter, boot the lappy wait for 2-3 minutes, stick the voltmeter prongs on the contacts where fan goes and see if it registers a current (some bios's will refuse to boot if no fan detected but there shoudl still be cuurent to the fan if the power is on). If it does the fans a dud, if it don't oh well new lappy time...dear Santa......