Conversion failed when converting the nvarchar value to int in SQL

Hi all,

 I need to find sum of the column name.

i have tried with the below code but am getting below error,

please drop me a solution for this.

select ' + sum(cast(@Scolumns as int)) + '  as Total  FROM #temp_MatchesTotal';

Error msg:

Conversion failed when converting the nvarchar value ',ISNULL([2015_April], 0) AS [2015_April],ISNULL([2015_August], 0) AS [2015_August],ISNULL([2015_July], 0) AS [2015_July],ISNULL([2015_June], 0) AS [2015_June],ISNULL([2015_May], 0) AS [2015_May]' to data type int.

thanks in advance.