Custom indexing connector for Azure blobs not crawling

Hi all,
I am creating a custom indexing connector for Azure blob. It works fine if i just specified URL for single blob e.g. for myblob://searchconnector.blob.core.windows.net/MyBlob/mycontainer/myblob1.txt
it just crawls http://searchconnector.blob.core.windows.net/mycontainer/myblob1.txt. Where myblob is protocol and MyBlob is entity type

But if i want to crawl all blobs of container using
myblob://searchconnector.blob.core.windows.net/MyContainer/mycontainer
then getting exception.
Finder method to get blobs is called and then correct access URIs for each blob  are created by
GetAccessUri(IEntityInstance entityInstance, IEntityInstance parentEntityInstance)
after that it fails by this exception
"Error while crawling LOB contents. ( Error caused by exception: System.ArgumentException Internal error: Too few parameters in Method. )".

Any help will be appreciated as I am not able to figure out why this exception occurs. I am following Custom File System Connector to develop this.