cDNA and it`s gene

[Li Bing]

Hi All,
Why I can`t amplify a gene which I have known the sequence of cDNA?
Recently I sequenced a cDNA which the coding area is only 180bps. Using
first 20 bps of coding area as 5`end primer, 20bps non-coding area of
3`end as another primer, I couldn`t amplify anything. Could anybody tell
me some reason of this? I don`t think it is a problem of optimization.

Thank you in advance

Li