A quick search on MSDN shows there could be several things that can cause this. You'll have to work through each one until it works

http://www.bing.com/search?q=Communication+with+the+underlying+transaction+manager+has+failed.&qs=n&form=QBRE&pq=communication+with+the+underlying+transaction+manager+has+failed.&sc=1-65&sp=-1&sk=&cvid=51d3d48d23464048854ebebd45f8282f



>Hi
>I am having issue on MSDTC. But I am not sure which category to choose.
>
>I have my Web app using MSDTC for multiple database transaction. It was working fine for all customers except one. I have used dtcping to ping on both server,
>
>

>DB
>---
>
>Please send following LOG to Microsoft for analysis:
>	Partner LOG: SBHRAPDEV1260.log
>	My LOG: SBHRMDEV1708.log
>++++++++++++Start Reverse Bind Test+++++++++++++
>Received Bind call from SBHRAPDEV
>Trying Reverse Bind to SBHRAPDEV
>Reverse Binding success: SBHRMDEV-->SBHRAPDEV
>++++++++++++Reverse Bind Test ENDED++++++++++
>++++++++++++Validating Remote Computer Name++++++++++++
>Please refer to following log file for details:
>	E:\DTCPing\SBHRMDEV1708.log
>Invoking RPC method on SBHRAPDEV
>RPC test is successful
>++++++++++++RPC test completed+++++++++++++++
>++++++++++++Start DTC Binding Test +++++++++++++
>Trying Bind to SBHRAPDEV
>Received reverse bind call from SBHRAPDEV
>Binding success: SBHRMDEV-->SBHRAPDEV
>++++++++++++DTC Binding Test END+++++++++++++
>
>
>
>APP
>---
>++++++++++++Validating Remote Computer Name++++++++++++
>Please refer to following log file for details:
>	C:\DTCPing\SBHRAPDEV1260.log
>Invoking RPC method on SBHRMDEV
>RPC test is successful
>++++++++++++RPC test completed+++++++++++++++
>++++++++++++Start DTC Binding Test +++++++++++++
>Trying Bind to SBHRMDEV
>Received reverse bind call from SBHRMDEV
>Binding success: SBHRAPDEV-->SBHRMDEV
>++++++++++++DTC Binding Test END+++++++++++++
>Please send following LOG to Microsoft for analysis:
>	Partner LOG: SBHRMDEV1708.log
>	My LOG: SBHRAPDEV1260.log
>++++++++++++Start Reverse Bind Test+++++++++++++
>Received Bind call from SBHRMDEV
>Trying Reverse Bind to SBHRMDEV
>Reverse Binding success: SBHRAPDEV-->SBHRMDEV
>++++++++++++Reverse Bind Test ENDED++++++++++
>

>
>It seem OK, but in my application, I hit error
>
>

>Communication with the underlying transaction manager has failed. 
>
>Communication with the underlying transaction manager has failed. The 
>
>MSDTC transaction manager was unable to pull the transaction from the 
>
>source transaction manager due to communication problems. Possible 
>
>causes are: a firewall is present and it doesn't have an exception 
>
>for the MSDTC process, the two machines cannot find each other by 
>
>their NetBIOS names, or the support for network transactions is not 
>
>enabled for one of the two transaction managers. (Exception from 
>
>HRESULT: 0x8004D02B)
>

>
>I have disabled firewall as well, but still not working.
>
>Please advice.