Dual Pricing mod for zen cart 1.3.7.1 ?

I was wondering if the Dual Pricing module for 1.3.7 is ok for zen cart v. 1.3.7.1
I have a test local zen cart v. 1.3.7.1 running on a winxp machine and everything was working ok, until I added the above module (for 1.3.7 zen cart). When I try to login as a customer, the system returns me to the same login page, i.e. there hasn't been any login (regardless of being a retail or wholesale customer). In other words, it seems that the login procedure cannot function. Everything else works ok regarding the dual pricing module (ie the wholesale input boxes appear as expected in the admin). Could the reason be an incompatibility between zen cart 1.3.7.1 and the dual pricing module (which is written for 1.3.7) or is it another reason (e.g. cookies, etc) ? I appreciate any help...

ok, I found out that the culprit is the browser itself (ie Firefox). In IE everything works ok. Something related with the options in Firefox doesnt let the attempted logged in customer keep the login status. (cookies, session variables, ???)

BUt I still would like to know if the dual pricing module for 1.3.7 is fully compatible for 1.3.7.1 zen cart version. (have there been recorded any problems ?)