Inconfirmed .LAS fie

HI,

Tried to types of image process;

First with only 17 images taken woth Phanto 4Pro v.2 but couldnt get confirmed .las file;

Second: 80 images taken from no 61 photo  and couldnt get confirmed .las fil.

My first trial starting from initial photo at take off down to photo 40 could get confirmed .las file.

What is the problem with first two trials?