concatenate will not paste special

Hi
I am trying to concatenate first name and last name columns, all is good
till I copy and paste special.....It say copy and paste area is not the same
size...and it is. Here is the real dilemma, when I copy and past the data
into a new spread sheet and concatenate it works, except in certain records
it drops the actual name and I end up with a blank field, that causes great
grief when I send said data to another process that strips blank lines and
shifts remaining data up resulting in an absolute train wreck of srong names
to addresses. Help