How to correct an IIF statement in SQL Server 2005?

I am developing a C# Web site application. I use VS2010 and SQL Server 2005.

Why does the following SQL statement give me an error as follows:
Incorrect syntax near '='.

The offending statement is:

IIf(sign_='-',CDbl(tbl_SMR_OI_DRS.amount*(-1)/100),CDbl(amount)/100),

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The entire SQL statement is as follows:
SELECT tbl_SMR_OI_DRS.bankNum, tbl_SMR_OI_DRS.officeNum, checknum, tbl_SMR_OI_DRS.refnum,
tbl_SMR_OI_DRS.transDTMnth + '/' + tbl_SMR_OI_DRS.transDTday + '/' + tbl_SMR_OI_DRS.transDtYR,
tbl_SMR_OI_DRS.tranType,
tbl_SMR_OI_DRS.processDTMnth + '/' + tbl_SMR_OI_DRS.processDtDay + '/' + tbl_SMR_OI_DRS.processDTYear,
tbl_SMR_OI_DRS.pending, tbl_SMR_OI_DRS.age*1, tbl_SMR_OI_DRS.cr_db, tbl_SMR_OI_DRS.descr,
IIf(sign_='-',CDbl(tbl_SMR_OI_DRS.amount*(-1)/100),CDbl(amount)/100),
tbl_SMR_OI_DRS.userID,
tbl_SMR_OI_DRS.auditDate, ' ', ' ', tbl_SMR_Banks.rptID, tbl_SMR_Banks.[REPORT NAME]
FROM tbl_SMR_OI_DRS INNER JOIN tbl_SMR_Banks ON tbl_SMR_OI_DRS.bankNum=tbl_SMR_Banks.[Bank Code];