This is usually a sign that the survey is too big.
MSSQl only support a certain number of columns. Try removing some of the questions/groups.

Not too big, only 12 questions, and I have activated it before. Here is an additional error message:

Internal Server Error
CDbCommand failed to execute the SQL statement: SQLSTATE[42S01]: [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]There is already an object named 'PRIMARY' in the database.
An internal error occurred while the Web server was processing your request. Please contact the webmaster to report this problem.

Is there something else we can try? Thanks.

I am having some issues after a port to a new install as well and realized that we have some inconsistencies between the ls_surveys, the lssurvey tables and the lstoken tables. Are yours consistent? Just a thought...

How do I check?

If you have access to the database you can run some SQL queries. I have a start for them... Sorry, the below is ugly, just pasting it from my notes. If you run the individual select queries I think they should all come back empty. Mine did not, still troubleshooting why and what to do now.

in ls_surveys but no table (I think this should be empty but may misunderstand how LS handles this)
SELECT sid, s_id
FROM ls_surveys

    left join 
    (select `TABLE_NAME`, mid(`TABLE_NAME`, length("ls_survey_")+1) as s_id
    from information_schema.tables 
    where table_schema = "cpdtrack_ls2"
    and locate("ls_survey", `TABLE_NAME`) = 1
    and locate("_timings", `TABLE_NAME`) = 0
    and mid(`TABLE_NAME`, length("ls_survey_")+1) REGEXP '[0-9]') as survey_tables

    on ls_surveys.sid = survey_tables.s_id

    where `survey_tables`.s_id is null

in tables but not in ls_surveys (I think this should be empty but may misunderstand how LS handles this)
select * from

    (select `TABLE_NAME`, mid(`TABLE_NAME`, length("ls_survey_")+1) as s_id
    from information_schema.tables 
    where table_schema = "cpdtrack_ls2"
    and locate("ls_survey", `TABLE_NAME`) = 1
    and locate("_timings", `TABLE_NAME`) = 0
    and mid(`TABLE_NAME`, length("ls_survey_")+1) REGEXP '[0-9]')  as survey_tables

    left join
    (select `TABLE_NAME`, mid(`TABLE_NAME`, length("ls_tokens_")+1) as s_id
    from information_schema.tables 
    where table_schema = "cpdtrack_ls2"
    and locate("ls_tokens_", `TABLE_NAME`) = 1) as token_tables

    on survey_tables.s_id = token_tables.s_id

    where token_tables.s_id is null

in languagesettings but not surveys (I think this should be empty but may misunderstand how LS handles this)
select *
from ls_surveys_languagesettings
left join ls_surveys
on ls_surveys_languagesettings.surveyls_survey_id=ls_surveys.sid
where sid is null

in surveys but not languagesettings (I think this should be empty but may misunderstand how LS handles this)
select *
from ls_surveys
left join ls_surveys_languagesettings
on ls_surveys_languagesettings.surveyls_survey_id=ls_surveys.sid
where surveyls_survey_id is null

Fix committed to master branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=16207

For the patch to work properly you will have to delete the already created survey_(you survey ID) table manually, once.

Has it been done already? Will we need to reinstall? I still get the following when trying to reactivate.

Internal Server Error

CDbCommand failed to execute the SQL statement: SQLSTATE[42S01]: [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]There is already an object named 'PRIMARY' in the database.

An internal error occurred while the Web server was processing your request. Please contact the webmaster to report this problem.

Thank you.

We are just preparing a new release. Either you patch it manually (see link above) or wait for the update.
As said, you will still need to delete the problematic response table manually on surveys where you already got the error.

Thank you so very much! Please have a great weekend.

Will that be 2.07?