CR 11 - "A string is required here"

I'm using Crystal Reports 11. I have a formula in which I keep getting the Error Message: "A string is required here". My code is below.

Code:

---

Dim dy, mo as string

mo = month(CDate({tblTimeSheetDetail.monDate}))
dy = day(CDate({tblTimeSheetDetail.monDate}))

formula = mo & "/" & dy

---

The error is occurring on the hightlighted line but will probably occur on the next line as well.

Thanks,

Unlike VB, Crystal does not automatically convert datatypes. The Month function returns an Integer so it needs to be converted to a string. Use CStr or ToText.

Unless things of changed in Version 11, Crystal has no Integer datatypes only a decimal type. The ,0 with the CStr function is used to specify the number of decimals to include in the string. Without it mo would equal "1.00"

mo = CStr(month(CDate({tblTimeSheetDetail.monDate})),0)

The dy line won't raise an error because dy is declared as a variant.