OBIEE Columns concatenation in answers

Hi,

I have a requirement where I need to concatenate 2 numerical columns in between '-'.

for ex: column1 value -  12345

column2 value - 67

then the result should be '12345-67'

I have used this statement in column formula

cast((column1) || '-' || ( column2) as varchar).

I am getting syntax error. Can somebody please help.

Thanks,

Seshu.