Attaching a .pdf file(s) into a form

Besides the script for the button's mouse up event, did you also add the Document JavaScript (import_file)?:

See JavaScript comments below:

// ADD THE FOLLOWING CODE FOR IMPORT BUTTON MOUSE UP JavaScript EVENT:

if (app.viewerVersion < 11) {

  import_pre_11();

} else {

  import_11();

}

// END CODE FOR IMPORT BUTTON MOUSE UP JavaScript EVENT:

// ADD THE FOLLOWING CODE TO Document JavaScripts:

// Acrobat menu>Advanced>Document Processing>Document JavaScripts

// Add Name = import_file

// Add - CODE START

// Initialize attachment number

attachment_num = 1;

// Initial location of file attachment icon

// The x value is incremented below

var oFAP = {x_init: -72, x: -72, y: -72};  // Below lower-left corner of the page

function import_pre_11() {

  if (app.viewerType === "Reader") {

  app.alert({

  cMsg: "You must user Reader version 11 or later to attach files to this form.",

  cTitle: "Attach File Error",

  nIcon: 3,

  nType: 0

  });

  return;

  }

  // Prompt user to import a file

  app.alert({

  cMsg: "Click the OK/Open button after selecting the file from your system that you want to attach.",

  cTitle: "Attach File",

  nIcon: 3,

  nType: 0

  });

  try {

  var rc = this.importDataObject("Attachment" + attachment_num);

  if (rc) {

  attachment_num += 1;

  app.alert({

  cMsg: "Attachment successful.\r\rOpen the Attachments panel to access the attached file(s).",

  cTitle: "Attachment Successful",

  nIcon: 3,

  nType: 0

  });

  } else {

  app.alert({

  cMsg: "Attachment cancelled.",

  cTitle: "Attachment Cancelled",

  nIcon: 3,

  nType: 0

  });

  }

  } catch (e) {

  app.alert({

  cMsg: "Could not attach file.",

  cTitle: "Could not attach file",

  nIcon: 3,

  nType: 0

  });

  }

}

function import_11() {

  try {

  var annot = addAnnot({

  page: event.target.page,

  type: "FileAttachment",

  author: "Form user",

  name: "File Attachment",

  point: [oFAP.x, oFAP.y],

  contents: "File attachment on: " + util.printd("yyyy/mm/dd HH:MM:ss", new Date()),

  attachIcon: "Paperclip"

  });

  annot.cAttachmentPath; // Prompt user to select a file to attach

  oFAP.x += 18;  // Increment the x location for the icon

  } catch (e) {

  app.alert({

  cMsg: "Could not attach file.\r\rPlease report this error.",

  cTitle: "File attachment error",

  nIcon: 3,

  nType: 0

  });

  }

}

// Document JavaScripts CODE END