Where contains throw Value can't be null

I'm stuck and don't know why this issue occurs.

Normally we do like this:

var q = await OrmDb.SelectAsync<OrmProductSerial>(p => p.SerialNumber.Contains(reqSearch) );

In this case I need do like this, but it throws an error. Doesn't ormlite support this ? ( linq can do it )

var q = await OrmDb.SelectAsync<OrmProductSerial>(p => reqSearch.Contains(p.SerialNumber) );

Thanks.