left trim error IMPORTANT

having an oracle prob.
Does anyone know what it is ?

Below is the where statement, on the line with the *** we get an error “invalid relational operator”
Any ideas?
How do you left trim a field in the where part of the clause with a right outer join ?

example.....
where
baandb.ttpppc275215.t$cprj (+)= baan.budget.project and
baan.budget.element = ltrim(baandb.ttpptc100215.t$cspa) and
**** ltrim(baandb.ttpppc275215.t$cspa) (+)= baan.budget.element and
baandb.ttpppc275215.t$csub (+)= baan.budget.subcon and
baandb.ttccom100215.t$bpid (+)= baandb.ttpppc275215.t$otbp and
baan.budget.subcon = baandb.ttppdm035215.t$csub and
baandb.ttpppc275215.t$amoc IS NULL and
baandb.ttpppc275215.t$fper (+)= baan.budget.period and
baandb.ttpppc275215.t$fyea (+)= baan.budget.yr
/

Left Outer join can be applied only to a column, not to an arbitrary expression, in other word you cannot use any function and column alias name with Outer join.

For more information about rules and restriction of Outer join, please go though the oracle documents.

Regards,