Azure data factory data flow expression builder

Trying to pull data from source using query:

concat('select column_name from {$trytable} where table_name =',$scddimname)

Both parameters declared and value assigned as:

scddimname string 'emp_scd'
trytable string'INFORMATION_SCHEMA.COLUMNS'

But, error

Error:
DF-DSL-001 - DSL stream has parsing errors
Line 9 Position 86: token recognition error at: '\n' - RunId: e93f18d2-cc0d-4b64-8336-15e75a5aaa22

Looks troubling!