Can't connect to MS SQL server from a 32 bit client

We have a lot of MS SQL 2008 R2 servers in different locations, and there were not problem to use them from a 32bit application. Today we were going to setup another MS SQL server (v10.50.4000, a second SQL instance) and the application server, but somehow I can not connect from a 32 bit application, but 64 bit client connects just fine.
To test a connection from a 32bit application I run the following command from 32bit cmd.exe:
\Windows\SysWOW64\Rundll32.exe "%CommonProgramFiles%\System\OLE DB\oledb32.dll",OpenDSLFile connect.udl
where connect.udl contains the connection string:
[oledb]
; Everything after this line is an OLE DB initstring
Provider=SQLNCLI10.1;Integrated Security="";Persist Security Info=False;User ID=username;Initial Catalog=DBname;Data Source=10.10.10.100\INSTANCENAME;Initial File Name="";Server SPN=""

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What I have tried: Reinstall the SQL native client to SP2. Checked the server's configuration manager (32bit client protocol is enabled).
Also tried to make a test connection from the server machine itself and from some other machine, works both 64bit and 32bit.
Also works from the problem application server to the main instance of the SQL server.
LVL 19
zc2Asked:
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zc2Author Commented:
Found a solution.
In the server configuration manager the second instance had defined alias with non standard TCP port.
The port has to be specified in the connection  string, like:
10.10.10.100,1435\INSTANCENAME
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Microsoft SQL Server 2008

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