When you try to register an agent you get random error messages when attempting to register it.
In the InTrust Event log you may also get that the agent was successfully installed, but it's not appearing in the agent list.
Some of the possible error messages are:
ADC Error: Agent doesn't have an established connection to InTrust server (0x8adc2c09)
ADC Error: Virtual connection doesn't exist (0x8adc2c05)
ADC Error: Two InTrust servers are trying to process each other using agents, or temporary network address resolution problem occurred (0x8adc2c1a)
ADC Error: Connection is closed (0x8adc2c07)
ADC Error: Buffer supplied is insufficient (0x8adc2c03)
ADC Error: Invalid credentials (0x8adc2c1c)