Convert Gregorian date to Julian date and use dateadd

I have a date field that is a decimal data type which I converted to datetime. When I use dateadd with the converted data type in SSMS 2005 it works but when I put this in SSRS 2008 I get the following error.

dateadd(dd, cast(right(lm.jha_dw_loaddate ,3) as varchar(3)) -1,
                   cast(left(lm.jha_dw_loaddate, 4) as datetime)) = @BeginDate + 7

Error Message: Conversion failed when converting the nvarchar value '4/10/2012 12:00:00 AM' to data type int

This works fine in SSRS 2008.

dateadd(dd, cast(right(lm.jha_dw_loaddate ,3) as varchar(3))-1,  
                   cast(left(lm.jha_dw_loaddate, 4) as datetime)) = @BeginDate

Any suggestions?