Numbers not adding together correctly
 

I am using Visual Basic to add numbers in a macro in an Excel spreadsheet.
Something has now changed to where the resulting value of the numbers to be
added is a string of those numbers instead of the sum.
This is the format of the formula I am using:
total.value = a.value + b.value + c.value
If a = 1, b = 2, c = 3, then total.value returns 123, not 6.
This is the case in the file I'm currently working on as well as any new
file which uses this same type of formula. I've tried searching for any
settings that might have caused it to produce this result and used VB and
Excel Help without any success so far. Please help. Thanks.