ToNumber - Crystal XI - convert string to number syntax

i have a field which is a string in the database, but i want to covert to a number so that i can format decimals etc.

i have tried

toNumber {table.field} 

but I get "the string is not numeric" - so not all are numeric or there are nulls?

then i tried the

If NumericText ({table.field}) Then

     ToNumber ({table.field})

Else

   0

but I get unwanted 0 showing up on the report.

i have tried

If NumericText ({table.field}) Then

     ToNumber ({table.field})

Else

   ({table.field})

but then I get "a number is expected here"

So what is the most efficient way to achieve this? i've read the posts about similar questions but not getting the answer that works for me.

thanks for all help! Jenn