After installing SQL, MOSS, PerformancePoint and Visual Studio 2008, I handed over the development environment , within a few minutes my co-worker was telling me he was getting errors when trying to connect to the PerformancePoint web service. I dug into it and found that the web service as well as the Preview site, calls for System.Web.Extensions version 1.0.61231.0, while, in our GAC, we had System.Web.Extensions version 18.104.22.168. I opened up the web.config files and changed all reference from 1.0.61231.0 to 22.214.171.124. This seemed to work fine, I could get to the Preview Site and access the web service.
Once again I let my co-worker have a go at it. He got a little further this time and then tried to publish his dashboard, and once again got an error, this time it was in the dashboard page itself though. At this point in time, due to some time constraints, we decided to bag the idea of switching everything over to System.Web.Extensions 126.96.36.199, so I uninstalled the .NET 3.5 framework (that installs with Visual Studio 2008), copied the System.Web.Extension and System.Web.Extensions.Design 1.0.61231.0 files from another machine into the GAC on my develop machine and everything works fine now.
My last remaining curiosity is, if make sure I install the .NET 3.5 framework before I install PerformancePoint, will PerformancePoint pick up on the newer version of System.Web.Extensions? If anyone knows leave a comment, and if I find the answer or have time to go back and give it a trial myself, I’ll post the results.