I found the error log, but this is not helping much.
Here is part of the error log:
[2C44:1D68][2016-05-06T10:55:17]i000: *** Begin all products log.
[2C44:1D68][2016-05-06T10:55:17]i000: ProductName=[Dell Toad Data Modeler], ProductVersion=[5.4.6.12], Publisher=[Dell], Context=[Machine], ProductCode=[{ACFAD021-FC02-4F2C-B7FB-5E3960D79368}].
[2C44:1D68][2016-05-06T10:55:17]i000: ProductName=[Toad for DB2 6.1], ProductVersion=[6.1.0.134], Publisher=[Dell], Context=[Machine], ProductCode=[{E121D023-F208-408E-AD48-0B6DE80CC7E3}].
[2C44:1D68][2016-05-06T10:55:17]i000: ProductName=[Toad™ for DB2 5.6 (64-bit DB2 Client)], ProductVersion=[5.6.0.2916], Publisher=[Quest Software], Context=[Machine], ProductCode=[{3E984923-240B-4A13-8091-2AA2CEF480D2}].
[2C44:1D68][2016-05-06T10:55:17]i000: ProductName=[Dell SQL Optimizer for IBM DB2 z/OS], ProductVersion=[5.5.0.332], Publisher=[Dell], Context=[Machine], ProductCode=[{C73BFF97-EBF1-41BC-9667-7C52492FE889}].
[2C44:1D68][2016-05-06T10:55:17]i000: *** EXCEPTION *** TargetSite=[Void LogAllInstallations()], Message=[Object reference not set to an instance of an object.].