Hi Mark - have just started adding this season's scoresheets to the on-line version. Entering an innings, realised I needed to add a player. Did this, but he then was not offered in the drop-down box. He appears in the list for the correct club, and is marked as 'active' (as advised in Q3 of the FAQs).
Only strange thing is when I look under 'list' in the team, he's in the 'Available' box, but not in the 'Selected' box on the right. If I highlight him and hit the arrow to transfer him, there's an error msg 'Max Team Size (40) Exceeded' - but there are several hundred names in the 'Selected' box.