The configured execution strategy 'SqlAzureExecutionStrategy' does not support user initiated transactions
In addition to suspending the execution strategy you also need to wrap the action you are retrying including the transaction in a manual call to the execution strategy, see my answer to How to use SqlAzureExecutionStrategy and "Nolock"
make sure you wrap the whole thing in a try/finally to be sure you set the suspend flag back to false. also have a look at this link for a detailed explanation: help link