Error in drool file: input mismatch -

i working on drool file below code:

    rule "test rule"     @rulenumber(1)     @rulemessage("data mismatch") when     $myobj : myobj($localval1: val1)      $datamismatch: boolean() ($localval1 == null)      eval $datamismatch    //do end 

i keep getting error mismatched input '$datamismatch' in rule, parser returned null package

does know going wrong?

thanks!

unless paid lines of code written, should use:

rule "test rule" @rulenumber(1) @rulemessage("data mismatch") when   $myobj : myobj(val1 == null)   //do end 

(looking syntax errors cannot done reliably without knowing drools version, haven't provided.)