PredicateBuilder issue with ServiceStack OrmLite -

i using servicestack ormlite predicatebuilder build statement dynamically:

   var q = predicatebuilder.true<itemlist>();     if (!filter.keyword.isnullorwhitespace())    {          q = q.and(i => i.brand.contains(filter.keyword) ||      i.itemdescription.contains(filter.keyword) || i.serial.contains(filter.keyword));    }     if (!filter.itemstatus.isnullorwhitespace())    {          q=q.and(i => i.itemstatus == filter.itemstatus);    }     var count = await db.countasync(db.from<itemlist>().where(q)); 

if none of if statements conditions met, error on executing query:

an expression of non-boolean type specified in context condition expected, near 'order'

the reason query generated is:

select [list of fields] itemlist true

update: using sql server 2012 dialect provider.

and not valid, expected behaviour?

i can use boolean check if condition being met , apply predicate expression, cumbersome.

i expecting if using predicate without added clause get:

where true=true

or equivalent.

is correct way of using predicatebuilder?