Annotation creation in pdf using PDLayer apis

Dear Friends,

I was trying to create annotation in pdf. While debugging I am able to see that the annotation objects are created but I can't see it in the pdf in the acrobat viewer application.
The code I tried is as below.

   pdAnnot =PDPageCreateAnnot (PDDocAcquirePage (pdDoc, pageNo), ASAtomFromString("Square"), &result);

  if(!PDAnnotIsValid(pdAnnot) )

       PDXlateToPDFDocEnc(str, str, strlen(str));

  textAnnot = CastToPDTextAnnot(pdAnnot);

  PDTextAnnotSetContents(textAnnot, str, strlen(str));

  PDAnnotGetRect(textAnnot,&test);

  PDAnnotSetFlags(pdAnnot, pdAnnotPrint);