RACE kit (Rapid Amplification of cDNA ends) is used for amplification of 3' or 5' of cDNA. If you need to amplify the whole length of cDNA you need a good reverse transcriptase, not RACE kit. I suggest you to use SuperScript® III Reverse Transcriptase from Life technologies
Hi Sarit, if you want to amplify uncharacterized gene ( I guess you know at least a little piece of its sequence) you can use BD SMART RACE from Clontech (it is working perfectly). Like that you can isolate 3' and 5' end of this gene (as Anna mentioned above RACE is for that) and once you have the 2 ends of the gene you can design primers flanking the full cDNA and use a very good reverse transcriptase as Anna suggest to amplify the whole molecule. Good luck!