There is a bug on Magento if you try to select numeric SKU. If you are trying something like:
[code]print_r($client->catalogProductInfo($session, “12345678”));[/code]
If you get this error:
[code]Product not exists.[/code]
And you are sure this SKU exists, your magento has this bug.
A fast workaround is add for example a space to the string, to have this:
[code]print_r($client->catalogProductInfo($session, “12345678 “));[/code]
Note the space after the 8.