Run the commands in the right panel.
XQuery is case-sensitive. This is very different from SQL where all commands and text are folded to uppercase unless the values are placed in quotes. The following examples show the difference using variables in XQuery.
$A and $a are two different values. Try correcting the error by changing upper case $A to lower case $a.
You should see an error returned in the lower right panel unless you changed the A to a.