Laravel IIS - 'There is no existing directory at' ... Log Path

Ill got a problem with my log files in Laravel 5.1 on Windows 2008R2 with IIS7.

When there is an error, laravel is unable to write it to the error log. In my php_errors log there is the following error reported:

[01-Oct-2015 11:24:24 UTC] PHP Fatal error:  Uncaught exception 'UnexpectedValueException' with message 'There is no existing directory at "C:\inetpub\wwwroot\webservice\storage/logs" and its not buildable: File exists' in C:\inetpub\wwwroot\webservice\vendor\monolog\monolog\src\Monolog\Handler\StreamHandler.php:141
Stack trace:
#0 C:\inetpub\wwwroot\webservice\vendor\monolog\monolog\src\Monolog\Handler\StreamHandler.php(77): Monolog\Handler\StreamHandler->createDir()
#1 C:\inetpub\wwwroot\webservice\vendor\monolog\monolog\src\Monolog\Handler\AbstractProcessingHandler.php(37): Monolog\Handler\StreamHandler->write(Array)
#2 C:\inetpub\wwwroot\webservice\vendor\monolog\monolog\src\Monolog\Logger.php(289): Monolog\Handler\AbstractProcessingHandler->handle(Array)
#3 C:\inetpub\wwwroot\webservice\vendor\monolog\monolog\src\Monolog\Logger.php(565): Monolog\Logger->addRecord(400, Object(Symfony\Component\Debug\Exception\FatalErrorException), Array)
#4 C:\inetpub\wwwroot\webservice\vendor\laravel\framework\src\Illuminate\Foundation\Exceptions\Handler.php(49): M in C:\inetpub\wwwroot\webservice\vendor\monolog\monolog\src\Monolog\Handler\StreamHandler.php on line 141

I guess this a path problem, because of C:\inetpub\wwwroot\webservice\storage / logs ? and not C:\inetpub\wwwroot\webservice\storage\logs - but where to change that? Ill found in the documentation that this is only changeable in L4.

All paths exists and all directorys in storage got write access for the IUSR.

Any ideas? Thanks in advance.

via Chebli Mohamed