Good pointer from bandit00...
...also, you don't specify the vintage of Excel you're running, but if you're using 2k, check this out :
"When an Excel spreadsheet that contains a macro is invoked, it will prompt you to enable the macro. Excel will stop the SAS DDE program from executing until the user responds to the prompt. To disable the prompt, do one of the following:
For Excel 2000 only. You cannot do this with earlier versions of Excel.
Option 1 - Use medium security
1 Choose security level.
a Select Tools>Options>Macro.
b Select Security Level tab and select Medium.
2 Create macros that have a digital certificate.
a Rerun the Microsoft Setup program.
b In Select Features, expand Office tools.
c Select Digital Signature for VBA projects and select
My Computer>Run.
d In Windows Explorer>Office, double-click SelfCert.exe.
3 Sign the macro.
a Select Tools=>Macro and then select the Visual Basic Editor.
b In the Project explorer, select the project you want to sign
c Select Tools>Digital Signatures.
d To use the current certificate, select OK.
4 Add the source.
a Select Tools>Macro>Security Panel.
b Select Trusted Sources tab.
Option 2 - Use low security
1 Select Tools>Options>Macro.
2 Select Security Level tab and select Low.
Note: use this option if your virus scanning software is very good.
Caution: selecting Low level ensures that Excel will not check for macro viruses."