Missing Plugins error when opening old file

 
As the subject says, plugins that are very much in my vst bank are showing as missing when I open an old file. Here are the screenshots of the error message when opening and the synth rack which shows the plugins as greyed (except TTS-1 which works) :
 

 
 

 
 
 
 
Could anyone fathom why this could be happening ? The project was initially created on an older Sonar version, X1 I think 
I could of course insert new instances of the synths and route the midi files to them, but that would mean I have lost all the synth settings that should be saved with the project.

 
 
Oh yes, I am pretty sure I was on a 32-bit machine when I first worked on that file. But all those plugins are now 64-bit only except FM8 which actually is still 32-bit, I mean I have retained 32-bit for FM8 though a 64-bit version exists due to a peculiar error in 64-bit FM8. But surprisingly, FM8 doesn't work too.
 
How do I sort this out ?
Do I need to have 32-bit versions of all plugins in addition to 64-bit in my system in order to open older files with all settings intact ? If I do, how and where do I tell Sonar Platinum to include both the 32-bit and 64-bit versions of the same plugin when it scans ? The paths for both bit versions are already defined by me and entered in the vst scan paths. But Sonar only shows the 64-bit version where there is one. It shows 32-bit version only for those plugins which have only 32-bit versions.

scook
Old plug-ins may require SONAR running as administrator. Is it possible the NI plug-ins in the old project were 32bit DirectX format? If so, there is no way for SONAR to replace them with 32/64bit VST equivalents.

Well, I am the only user on my computer and run it with administrator status.
 
I am not sure about the DirectX part but as far as I remember, only some Cakewalk plugins have been DirectX on my setup and NI have always been VST since I stated using them. Moreover, for that matter, TTS-1 is a Cakewalk DirectX plugin, and thats the only one that seems to be working for me on this project as I open it !