Hey Azeez,

This error may be due to many reasons. There was no data for prices for the period u were trying to test or some currency symbol problems.

Please see this thread – https://www.mql5.com/en/forum/154449
And, please ensure that u have data downloaded for the MT4 for the period u want to test.
You can check Historical data section here – http://www.spheretester.com/user-guide/#Historical_data

Thanks,
Aayush