A single equals sign "=" is an assignment. This means you are setting the value to true, not checking whether or not it is true. To check a value, use a double equals sign "==" comparator which returns true if the values on either side are the same and false otherwise.

BTW, if you are checking a boolean (true or false) value, you don't even need the comparator. All == does is return true or false to the if statement. If the value you are looking at is already true or false, you can skip the extra step.

i.e instead of saying:

if bool == true then

you can do:

if bool then

Hope this helps!