I have a DFT that creates a cached transformation to insert rows into a cache file. There are only about 15 rows.
Following on from this there is another DFT that has a lot of transformations, three of which are lookups that lookup data against coming through the pipeline againts data retrieved from the cache file. The first transformation that does this has no problems. The DFT task however fails when the second lookup transformation attempts to lookup against the same cache file.

The following error is seen:
[LKP PickUp Country Key [767]] Information: The system cannot find the file specified.Failed to load the cache from file, "L:\CCM_Country"
component "LKP PickUp Country Key" (767) failed the pre-execute phase and returned error code 0xC020930C.
The raw adapter attempted to read 4 bytes in the input file for column "CountryKey" with lineage ID 1, but there was an error. The error returned from the operating system should have been previously reported.
Cannot read 4 bytes from file "L:\CCM_Country". The cause of the failure should have been previously reported.

The cache file does exist on the L: drive and the account running SSIS has full permissions. If I move the second transformation to the end of the pipeline then the DFT succeeds with no errors.
Therefore it appears that in certain circumstances where a DFT has Lookup transformations that are next to each other in the pipeline that pull data from the same cache file it produces an error.
This goes against the principle of using cache connections in that they are supposed to be used by multiple lookups in the same DFT or across multiple DFT's.