crontab test argument expected

Hello folks,
I've got this script which runs perfectly when i run it manually. But when i am running it from a crontab i am getting an error saying
test argument expected.
The line from where it is coming is something like this:
if [ -e file.txt ]
then
do something
fi

Any idea why?

Check the script for execution permissions. Crontab required the execution permission..

Set PATH or use the full path when you do something