Flex Project(Maven): Getting Compilation error on Flash Builder 4.7 but compiles successfully on RTC -

my project created in previous version of flash builder(fb) , using fb 4.7, when change flex server properties on fb, face compilation errors.

if not change flex server properties there no compilation error(though properties pointing wrong location).

flex properties must not change?

error:

[error]     c:\cmslite\test2\rtcmlite\src\valueobjects\_departmententitymetadata.as:[170,30] method marked override must override method. override public function getpropertytype(propertyname:string):string [info] ------------------------------------------------------------------------ [info] reactor summary: [info]  [info] cmslite ........................................... failure [16.422s]