Azmat Jahan If you mean that you have a uni-dimensional scale and you are trying to run a confirmatory factor analysis then you can do it with other scales of the research.but if you just want to do a confirmatory factor analysis of one scale which is uni-dimensional then you cannot.
At least 3 indicator per factor is advised. Cattel (1988) advised at least 2 indicator per factor. I think you should have 2 idicator per factor to conduct EFA or CFA.
In SmartPLS you can not perform CFA analysis with only one dimension with their measurement items. You need a model with at least two dimensions or factors. If not, pls algorithm button does not work.