temp variables in Oracle Express failure

 Oracle Express vsn. 6.3.2.16 - issue with the defining the variable as a temporary.

The statement to define a variable as a temporary in the standard Oracle Express api (ofa.api.init) fails (sometimes - api returns a null value for this variable ifdefined as temporary and is OK if defined as a usual permanent ). It wasn't always this way but started after 8 years of the successful call of this api. What could cause such a failure? What a difference between permanently defined and temporary variable for Express that can make a difference when 'temporary' is commented out and api returns value just fine...