Conversion failed when converting date and/or time from character string dynamic sql

[spawk]

I've got a bit of dynamic SQL I'm running that is working fine when I manually write in the variables, but as soon as I then change them from the manually written in to actual variables, I get the error above.The code is:\[code\]set @query = 'SELECT eng, ' + @colsNull + ' from ( select eng, [count], cast(weekof as date) weekof from dbo.RPT_ENG_WEEK (''1 jan 2013'', ''9 apr 2013'', ''1 jan 2013'', ''9 apr 2013'') ) x pivot ( sum([count]) for weekof in (' + @cols + ') ) p '\[/code\]Which works fine, but as soon as I change it to \[code\]set @query = 'SELECT eng, ' + @colsNull + ' from ( select eng, [count], cast(weekof as date) weekof from dbo.RPT_ENG_WEEK ('+@from+', '+@to+', '+@start+', '+@end+') ) x pivot ( sum([count]) for weekof in (' + @cols + ') ) p '\[/code\]I get the error. I've also tried\[code\]set @query = 'SELECT eng, ' + @colsNull + ' from ( select eng, [count], cast(weekof as date) weekof from dbo.RPT_ENG_WEEK ((select CONVERT(DATE'+@from+',105)), (select CONVERT(DATE'+@to+',105)), (select CONVERT(DATE'+@start+',105)), (select CONVERT(DATE'+@end+',105))) ) x pivot ( sum([count]) for weekof in (' + @cols + ') ) p '\[/code\]But to no avail!Have also tried \[code\]from dbo.RPT_ENG_WEEK ((select CONVERT(DATE'''+@from+''',105)), (select CONVERT(DATE'''+@to+''',105)), (select CONVERT(DATE'''+@start+''',105)), (select CONVERT(DATE'''+@end+''',105)))\[/code\]and\[code\]from dbo.RPT_ENG_WEEK ('''+@from+''', '''+@to+''', '''+@start+''', '''+@end+''')\[/code\]