Bash error : [: missing `]'

I would like to implement a quite simple function but an error occurs on the condition used.

function test()
{   
    checkstatus
    echo ${currentStatus}
    if [ "$currentStatus" == "true" ] 
    then    
        echo "Currently Ok"
    else
        exit_error 101  
    fi
}
test

However the script returns :

true

./script.sh: line 4: [: missing `]'