OK, a simple thing I know. But one that always occurs.
When using shared hosting (or even your own dedicated servers), those managing those servers do their utmost to make them secure. Among many things this usually includes turning off ‘display_errors’ in the php.ini file.
However, when you’re trying to develop things it is usefull to display errors and warnings, but if ‘display_errors’ is off, you will be scratching your head wondering what’s going on and whats going wrong!