I don't have an MS SQL with me right now to try this out. But looking at the error, can you restart the WFA server service with SQL Server domain credentials and re-try acquistion. I'm not sure, but this will work or not.
Alternative:
Create a DataSource Type(DST) of method script. The script DST is way too powerfull compared to connection using JDBC drivers. Slower but it can do anything and everything. This will definitely get you whatever you want. You execute the same queries you planned to execute and get data.
sinhaa
If this post resolved your issue, help others by selecting ACCEPT AS SOLUTION or adding a KUDO.