Merging catalogs and moving files

Hi,

New to forum and need help with catalogs. Im using Lightroom CC, newest updates, on a 2014 15" MacBook Pro. I recently returned from vacation,  all of my photos taken  while traveling were stored in a new catalog  on a new Lacie 1tb external drive.  

Upon returning home I wanted to move these photos and merge the catalog to my master catalog and main storage drive.   I had viewed Julieanne Kost videos several times prior to importing and searched this forum for additional help prior to doing this.

I used "Import From Another Catalog",   selected  "move files to new location" in the drop down menu.  All of the folders at top of menu box were checked,  destination drive (Main storage drive) was selected  from the "Choose menu", the path looked correct then I hit "ok".

Lightroom failed to import all my photos and merge the catalog. Im  missing photos, and folders,  and it did not merge the travel  catalog with the master catalog.  The photos that did import were imported in a random unorganized order and exclamation icons are showing on the photos that did import to master catalog and main storage drive.  I have to go to the Lacie external drive and re-open the travel catalog to find the photos that did import and the 1,100 missing photos that did not import.  What did I fail to do?

Thank You

Jim Brennan