Dolly,
Don't think your answer is correct. Don't have access to the books at the minute but I seem to remember that the Landing Gear Transfer unit operates by using SYSTEM B FLUID FLOW to pressurise SYSTEM A FLUID. In other words it caters for a loss of flow rate of system A fluid due to loss of A system engine-driven pump following an engine failure on takeoff. However, if there has been a major leak in system A then there may be no fluid left for the LGTU to pressurise - if no A fluid, gear cannot be retracted.
I stand to be corrected...