sqlcesa35.dll merge process error - trying not to reinitialize subscriptions

I have an SQL Server 2008 R2 with a local publication and distribution on one machine.
On another machine I have Windows Server 2003 and IIS 6 with the SSCE server tools installed and an IIS application that I use to sync my WM6 devices with the first machine through sqlcesa35.dll.

My issue is that the WS2003 machine has to be decommissioned and I have to move the sqlcesa35.dll to a WS2008 R2 machine with IIS 7.5. I have installed the same SSCE server tools version in this IIS 7.5 and as far as I know created the IIS application identical to the one on WS2003.

When I try to sync a WM6 device through the IIS 7.5 application I get the following error message in the replication monitor:

  • The process could not initialize 'SQL Server CE Subscriber'. Verify that the component is registered correctly. (Origen: MSSQL_REPL, Número de error: MSSQL_REPL-2147198716)
    Obtener ayuda: http://help/MSSQL_REPL-2147198716
  • The merge process could not connect to the message file from Subscriber '{3EDB269D-F187-A528-C0C4-09B7ECA2DE11}:D:\websites\MyReplApp\35.6E23356D9D26_4C658BEF-4521-C3A2-775C-6465DD6BB616.IN'. Check to ensure that the server is running. (Origen: MSSQL_REPL, Número de error: MSSQL_REPL-2147198719)
    Obtener ayuda: http://help/MSSQL_REPL-2147198719
  • The subscription to publication 'MyDBPub' could not be verified. Ensure that all Merge Agent command line parameters are specified correctly and that the subscription is correctly configured. If the Publisher no longer has information about this subscription, drop and recreate the subscription. (Origen: MSSQL_REPL, Número de error: MSSQL_REPL-2147201019)
    Obtener ayuda: help/MSSQL_REPL-2147201019

This means that the IIS 7.5 app is responding (and I can confirm with sqlcesa35.dll?diag) but somewhere there's a break between the IIS and the SQL Server.
I want to avoid reinitializing the subscriptions at all costs because this is a production environment. Any help on getting this to work would be much appreciated.

I think for this issue that you are going to need to open a support case with Microsoft.

I saw that sqlcesa35.dll?diag gave me the following:

SQL Server Compact Modules Test
Module Status ErrorCode Version
sqlcerp35.dll FAILURE 80040154 Unknown
sqlcesa35.dll SUCCESS 0x0 3.5.8080.0

Turns out that the IIS application pool had 32bits enabled and this was blocking sqlcerp35.dll. I disabled this and now everything works.