How do i find which variable is undefined? (flash builder)

A flash application in flash builder is currently throwing this error:

ReferenceError: Error #1065: Variable  is not defined.

Not telling me which variable it is that's not defined, but note there are two spaces between 'variable' and 'is'. and it gives me some more feedback as to what lines of code are having trouble, but those lines are all within the actual flash/mxml packages and not any of the files in my own project.

I suspect it's related to my php data/services, but I don't see what variable would not be defined. I'm not very familiar with debugging, so I'm not sure how to determine with it where the problem is cropping up.

at global/flash.utils::getDefinitionByName() at mx.utils::DescribeTypeCache$/describeType()[E:\dev\4.x\frameworks\projects\framework\src\mx\utils\DescribeTypeCache.as:106] at com.adobe.serializers.utility::TypeUtility$/getType()[/Users/sameer/depot/flex/ide_builder/com.adobe.flexbuilder.dcrad/serializers/src/com/adobe/serializers/utility/TypeUtility.as:90] at com.adobe.serializers.utility::TypeUtility$/assignProperty()[/Users/sameer/depot/flex/ide_builder/com.adobe.flexbuilder.dcrad/serializers/src/com/adobe/serializers/utility/TypeUtility.as:516] at com.adobe.serializers.utility::TypeUtility$/convertToStrongType()[/Users/sameer/depot/flex/ide_builder/com.adobe.flexbuilder.dcrad/serializers/src/com/adobe/serializers/utility/TypeUtility.as:498] at com.adobe.serializers.utility::TypeUtility$/convertListToStrongType()[/Users/sameer/depot/flex/ide_builder/com.adobe.flexbuilder.dcrad/serializers/src/com/adobe/serializers/utility/TypeUtility.as:454] at开发者_StackOverflow中文版 com.adobe.serializers.utility::TypeUtility$/convertResultHandler()[/Users/sameer/depot/flex/ide_builder/com.adobe.flexbuilder.dcrad/serializers/src/com/adobe/serializers/utility/TypeUtility.as:367] at mx.rpc.remoting::Operation/http://www.adobe.com/2006/flex/mx/internal::processResult()[E:\dev\4.x\frameworks\projects\rpc\src\mx\rpc\remoting\Operation.as:316] at mx.rpc::AbstractInvoker/http://www.adobe.com/2006/flex/mx/internal::resultHandler()[E:\dev\4.x\frameworks\projects\rpc\src\mx\rpc\AbstractInvoker.as:313] at mx.rpc::Responder/result()[E:\dev\4.x\frameworks\projects\rpc\src\mx\rpc\Responder.as:56] at mx.rpc::AsyncRequest/acknowledge()[E:\dev\4.x\frameworks\projects\rpc\src\mx\rpc\AsyncRequest.as:84] at NetConnectionMessageResponder/resultHandler()[E:\dev\4.x\frameworks\projects\rpc\src\mx\messaging\channels\NetConnectionChannel.as:547] at mx.messaging::MessageResponder/result()[E:\dev\4.x\frameworks\projects\rpc\src\mx\messaging\MessageResponder.as:235]

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look at line 106 for DescribeTypeCache.as There will likely be two variables, one of them is undefined