No results on my Probate Direct Mail campaign

[Matt Foster]

I started a direct mail campaign for Probates about 5 months ago and haven't received one call back.  I have a Virtual Assistant who pulls Executor/PR name & address from our local Legal newspaper and puts into an excel to create a prospecting list.  I've been mailing the PR's on a monthly basis (I'm just about to mail for the 6th consecutive month).  Every month I add about 160-200 new names.  My letter is simple.  I offer condolences, let them know I'm an investor who pays cash and that I can close quickly hassle-free.  Most of the material in the letter was generated from people who post in this forum with a lot of probate experience, so I'm confident the letter is at least adequate enough for SOME results! 

I know this niche is all about consistency and time, but to not get a single call is frustrating.  I'm also marketing to other niches with much more success but for one reason or another haven't been able to produce anything from Probates.  

Anyone else with this experience?