Unify! for Expression Blend

Hi everyone,
I am very glad to see such a add-in coming up but unfortunatelly I got the following error during install:
'Unify for Microsoft Expression Blend requires Blend 2 with SP1 to be installed.'
But that's exactly the version I have installed on my computer as the info box says:
Expression Blend 2 Service Pack 1, Version 2.1.1760.0 (German)

Anyone got the same problem or a suggestion what to do?

Thanks in advance, Rose M.

@Michael_Rose : Can you run the following from the command line from where the unify.msi is.

msiexec /i unify.msi /lvx unify.log and send the results to me please?

Thanks for your reply, I hope the relevant output of the command is contained in the following snippet, I can't post more in one comment, please let me know if you need further information.

Action start 22:03:37: INSTALL.
MSI (c) (00:BC) [22:03:37:078]: UI Sequence table 'InstallUISequence' is present and populated.
MSI (c) (00:BC) [22:03:37:078]: Running UISequence
MSI (c) (00:BC) [22:03:37:078]: PROPERTY CHANGE: Adding EXECUTEACTION property. Its value is 'INSTALL'.
MSI (c) (00:BC) [22:03:37:078]: Doing action: AppSearch
MSI (c) (00:BC) [22:03:37:078]: Note: 1: 2205 2: 3: ActionText
Action start 22:03:37: AppSearch.
MSI (c) (00:BC) [22:03:37:093]: PROPERTY CHANGE: Adding BLENDEXELOCATION property. Its value is '"c:\Programme\Microsoft Expression\Blend 2\Blend.exe"'.
MSI (c) (00:BC) [22:03:37:093]: Note: 1: 1402 2: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{3891e1c9-8e9e-43e2-b009-6d008bcd7669} 3: 2
MSI (c) (00:BC) [22:03:37:093]: Note: 1: 1322 2:
MSI (c) (00:BC) [22:03:37:093]: Note: 1: 1322 2:
Action ended 22:03:37: AppSearch. Return value 1.
MSI (c) (00:BC) [22:03:37:250]: Doing action: LaunchConditions
MSI (c) (00:BC) [22:03:37:250]: Note: 1: 2205 2: 3: ActionText
Action start 22:03:37: LaunchConditions.
MSI (c) (00:E4) [22:03:37:250]: Font created. Charset: Req=0, Ret=0, Font: Req=MS Shell Dlg, Ret=MS Shell Dlg

MSI (c) (00:BC) [22:03:38:234]: Note: 1: 2205 2: 3: Error
MSI (c) (00:BC) [22:03:38:234]: Note: 1: 2228 2: 3: Error 4: SELECT `Message` FROM `Error` WHERE `Error` = 1709
MSI (c) (00:BC) [22:03:38:296]: Product: Unify for Microsoft Expression Blend -- Unify for Microsoft Expression Blend requires Blend 2 with SP1 to be installed

Action ended 22:03:38: LaunchConditions. Return value 3.
Action ended 22:03:38: INSTALL. Return value 3.

Can you send the entire log to simon dot middlemiss at microsoft dot com

Following this up offline.