Custom Meta in Meta Query

Hi

we have a plugin that uses custom meta data and we need to pull a list based on one of these meta fields ‘xn-wppe-expiration-prefix’

but we cant seem to get it right.

we put the ‘xn-wppe-expiration-prefix’ in the Key field, select = as the Compare field, and then the relevant value in double quotes in the Value field “Expired”, but this doesnt return the posts with this meta from the database.

are we configuring the query correctly for custom meta?

thanks so much,
vauneen