Query Works SQL Server Studio Not Visual Studio

I have SSRS in Visual Studio. I created a query that works fine in SQL Server Management Studio, but when pasted into Visual Studio I get the error "An expression of non-boolean type specified in a context where a condition is expected, near '('.

Here is the query. Can anyone help on why this isn't working? Thanks.

SELECT CASE WHEN MONTH(dbo.MAS_CCS_ARN_InvHistoryHeader.SOTransDate) = MONTH(GETDATE()) AND YEAR(dbo.MAS_CCS_ARN_InvHistoryHeader.SOTransDate) = YEAR(GETDATE())
THEN dbo.MAS_CCS_ARO_InvHistoryDetail.SOExtChargeAmount ELSE 0 END AS CurrentMonth,
CASE WHEN SubString(dbo.MAS_CCS_GL_Account.Account,1,3) = '400' THEN 'ALEDO' ELSE ' ' END AS Location,
dbo.MAS_CCS_ARN_InvHistoryHeader.SOTransDate, dbo.MAS_CCS_ARN_InvHistoryHeader.InvoiceNumber,
dbo.MAS_CCS_AR1_CustomerMaster.CustomerName, dbo.MAS_CCS_ARO_InvHistoryDetail.DetailSeqNumber,
dbo.MAS_CCS_ARO_InvHistoryDetail.LineType, dbo.MAS_CCS_GL_Account.Account, dbo.MAS_CCS_ARO_InvHistoryDetail.SOExtChargeAmount
FROM dbo.MAS_CCS_AR1_CustomerMaster, dbo.MAS_CCS_ARN_InvHistoryHeader, dbo.MAS_CCS_ARO_InvHistoryDetail,
dbo.MAS_CCS_GL_Account
WHERE dbo.MAS_CCS_AR1_CustomerMaster.CustomerNumber = dbo.MAS_CCS_ARN_InvHistoryHeader.CustomerNumber AND
dbo.MAS_CCS_ARN_InvHistoryHeader.InvoiceNumber = dbo.MAS_CCS_ARO_InvHistoryDetail.InvoiceNumber AND
dbo.MAS_CCS_ARO_InvHistoryDetail.SOGLSalesAcct = dbo.MAS_CCS_GL_Account.AccountKey