Blank page when regular user submits new case and tries to edit a case

I am logged in as a regular user, I create a project then go to add a case. Everything is fine until I submit, then I get a blank screen. I see that the case is actually created when I view all cases for my project. I click on the link to view the created case and end up with a blank screen.

This does not happen when I am logged in as the admin. Also, if I login as a user different from the one who created the case, I can click on the link to view the project and have the page display.

I checked my apache logs and there is apparently an error with the casetracker_basic.module:

In access log when the page is blank I see lines like:
127.0.0.1 - - [22/Nov/2007:14:49:00 -0500] "GET /midi/node/49 HTTP/1.1" 500 -
127.0.0.1 - - [22/Nov/2007:14:52:46 -0500] "GET /midi/node/49 HTTP/1.1" 500 -
127.0.0.1 - - [22/Nov/2007:14:53:48 -0500] "GET /midi/node/49 HTTP/1.1" 500 -

In the error log I see lines like:
[Thu Nov 22 14:52:46 2007] [error] [client 127.0.0.1] PHP Fatal error: Call to undefined function dvm() in ...\\midi\\sites\\all\\modules\\casetracker\\casetracker_basic.module on line 139, referer: http://localhost/midi/casetracker/cases/48/all
[Thu Nov 22 14:53:49 2007] [error] [client 127.0.0.1] PHP Fatal error: Call to undefined function dvm() in ...\\midi\\sites\\all\\modules\\casetracker\\casetracker_basic.module on line 139, referer: http://localhost/midi/casetracker/cases/48/all
[Thu Nov 22 15:01:36 2007] [error] [client 127.0.0.1] PHP Fatal error: Call to undefined function dvm() in ...\\midi\\sites\\all\\modules\\casetracker\\casetracker_basic.module on line 139, referer: http://localhost/midi/casetracker/cases/48/all

Node 49 is the case I created and want to view, and the referer is the all cases page with the link to the case (node 49)