According to our developer such error will occured if you do not have .NET framework installed. Our installer will perform a check for the .NET framewrk by checking the v2.0.50727 .NET framework folder under Windows folder, default location C:\Windows\Microsoft.NET\Framework\v2.0.50727

Do you mind sharing where does the v2.0.50727 .NET framework folder located in your machine?

It is located at the exact same path : C:\Windows\Microsoft.NET\Framework\v2.0.50727

What exactly does it need ?

According to our developer the installer will only check if the folder is available however, we suspect the error could also occur if you do not have access to the Windows folder. Please try running the installer with administrator access.

I have tried to install with a user that is Administrator on the computer and also Domain Admin. I did "Run as administrator" to install and it still did not worked. I always get the same error.

Any other suggestions ?

We do not have anymore idea of what could cause the error message if you have already have .NET framework 2.0 installed and run the installer as adminstrator. Have you tried running the installer on another machine, does it also reproduce the same issue?  

I am not the only user who has this problem. Alex H got the same error as me. If his problem is solved, I don't have access to the solution because it was sent by email. Could you please check with Yudi because it seems that he sent an answer to Alex H.

see:

http://www.intersoftpt.com/Community/WebDesktop/Installation---NET-20-Required-Error-Message-When-35-is-Installed/

http://www.intersoftpt.com/Community/Lounge/Cant-Install-on-Server-2008-64-bit--Error-that-NET-Framework-is-not-installed-when-it-is/

http://www.intersoftpt.com/Community/Lounge/Windows-Server-2008-R2-Enterprise-64-problem-WebStudio-2009-R1/

I have discuss the issue with my colleague Yudi, who handle the thread listed. He mention that the above issue has not been solved and Alex H has not replied to us since his last post in the thread or through email.

Perhaps we could try to replicate the issue in our environment to investigate the issue further. Do you mind sharing the enviroment detail you are using to install the product? You already mention that you are using Windows Server 2008 SP2 with .NET Framework 3.5 SP1, is it the 64 bit version or the 32 bit one? 

I have :

 - Windows Server 2008 SP2 - 32-bit

 - Microsoft .NET Framework 3.5 SP1

 - Microsoft .NET Compact Framework 2.0 SP2

 - Microsoft .NET Compact Framework 3.5

 - Intersoft WebUI Studio .NET 2008 R2 SP1

 - Microsoft Visual Studio Team System 2008 Development Edition

And I want to install :

 - Intersoft WebUI Studio 2009 R2 SP1

Thank you very much for trying to replicate the issue.

Unfortunately, We do not have Windows 2008 R2 in our environment. However, we will try to installed the OS in our environment with the specification you desribed to further investigate the issue. It will take a few days to a week in order to prepare the system in our environment. We will inform you if there is any update.

I have tried the WebUI Studio 2009 R2 SP1 installer in the Windows 2008 SP2 environment with Visual Studio Team System 2008 installed. In my test the Visual Studio installation will also install the .NET Framework and .NET Compact Framework.

In my test environment however, the WebUI Studio 2009 R2 SP1 installation run successfully without any issue. The installer I used is intersoft webui studio 2009 r2 sp1.exe [387MB (406,717,881 bytes)].

In a few days, we will release WebUI Studio 2010 R1 RC, do you mind trying the RC installer to see if the issue still occur in your environment. Please check Intersoft site for the RC download link when the RC is available.

Thank you for trying. I will wait for the new version and hope that this one will work.

I also get this problem, it all worked, I updated to include the license, and there it goes, .NET framework 2.0 or greater required.  Stopped me working.    Also installing in Windows Server 2003 Server.

Hello,

Have you tried above suggestion? Sometimes, this error is also occured event though you've installed the framework. 
Please also ensure you update with latest service packs or updates. 

Regards,
Handy