OCS 2007 error creating pool

Hello everyone!
I am facing problem while trying to create pool backend with OCS.

Normally, I found this error "Pool backend discovery failed" but it also remained the same after reinstalling the Backwards compatibility.
I am using the SQL Express 2005 SP3.My database is in the local server while everything seems to be ok but failed to work.
Need a suggestion. Thanks.
Error:
An error occurred during the pool backend detection:
Failed to export pool backend configuration database settings.
Unable to get back the configuration database version..
Click 'Cancel' to close the wizard.
Click 'Try Again' to go back to the previous page and enter a different pool backend instance.
Click 'Continue' to move forward.
