Breakpoints are not getting hit

[MSK]

Dear all,

Continued to my earlier mail regarding "Breaking points are not getting
hit in ASP.NET " ,
I got some idea from net. Can anyone give me more idea on this?

Just to remind the issue:

1. I got the following error while executing a newly created a web
application (just sample app)
["Error while trying to run project: Unable to start debugging on the
web server"]
(Some what I can avoid this error: change Project
properties-->Configuration-->Debugging-->Enable SQL debugging - TRUE)

2. The break points are not getting hit

I got an idea from net to change the ASP.NET version in IIS for this
specific application.
1. I have the following Microsoft.NET Framework version in my laptop

1) V1.0.3705
2) V1.1.4322
3) V2.0.5727 (Recently installed)

I checked the ASP.NET version of the application, it shows V2.0.5727
and I changed the ASP.NET version in
IIS-->Web sites-->Default websites--<Project> -->Properties-->Asp.NET
version as V1.1.4322,

then I could execute the application without the above-mentioned error
and the break points are also getting hit.

1. What was the mistake?

If I create a new web app, the ASP.NET version will be 2.0.5727, I am
getting the same error, and then I need to change the version.

2. How to avoid this?

Many Thanks

Regards
MSK.