Says variable isn't declared, but was entered as a parameter

Says variable isn't declared, but was entered as a parameter

I am trying to fetch records where a field is greater than a parameter.
 
Using deluge...
 
I am passing a parameters into the function, criteria
 
I want to fetch records where Height of the item is larger than the criteria
 
items  =  item  [Height > criteria];
 
but it says
 
Error in statement at line number 1
The Left expression is of type BIGINT and the right expression is of type STRING And the operator > is not valid here
 
So if I try to set the variable by using criteria = .toLong(criteria) it says the cariable isn't declared.
 
Any help would be great