Apple Logic Pro /LogicExpress Discussion

I have a question and i welcome any and all feedback from group members.

i'm lucky(?) enough to have a client who wants an unspecificied number of music tracks for 
their ongoing DVD projects. I'm not charging a whole lot for these tracks because they 
wouldn't be able to pay what it would cost to own the copyright. so i'm licensing the music to 
them and retaining the rights. 

The procedure is typical. i create a demo, email them an mp3 and they approve or 
disapprove. 

Problem is lately, they've been turning down about 1/3 or more of the demos. i'm creating. 
so if takes me a day  to turn out a good demo, and they reject it, i make no money that day. 
it's now at a point where i can't afford to continue like this. 

just wondering if there's  standard procedure or protocol for this type of work situation. this 
is my first time out like this and i personally do not know any pros to put this question to, am 
kind of working in isolation here unfortunately, although i'm trying to change that. 

thanks in advance. maybe a discussion like this could help others too ; - )

Tom