Without any assistance from your company on getting your product to work, we have discovered the following problems with your Billing Mgr 2.5 installation:
1. Does not install the App_Webbillmgrsettings.ascx.61ca2ac0.dll
We have manually installed this dll and gotten past this issue.
2. Your install package is missing the ManageSubSettings.ascx file and associated dll.
From the error log:
The file '/DesktopModules/SmithBillingManager/ManageSubSettings.ascx' does not exist.
Please advise ASAP when we will have a corrected installation package.