I wonder if the problem comes from something like this:

WITH VTE AS(
SELECT *
FROM (VALUES('1'),('1.1'),('1.1.1')) V(S))
SELECT CONVERT(decimal(2,1),S)
FROM VTE
WHERE S NOT LIKE '%.%.%'
AND CONVERT(decimal(2,1),S) > 1 ;

This is not guaranteed to work every time and it's prone to errors as  t-sql is a declarative language and not a procedural language.