This error occurs when a trader (either manually or through an Expert Advisor) attempts to place a trade with a volume that exceeds the limits set by the broker. Possible causes include:
Taurex imposes specific volume limits for each trade, which vary depending on the account type and the time of day. If an attempted trade exceeds these limits, the "Invalid Volume" error will appear.
An Expert Advisor (EA) may be configured to open a trade with a volume that surpasses the permitted limits for the selected instrument or account type.
A manually placed pending order may not meet the volume limitations at the time it is executed. For example, if a trade for 100 lots reaches the expected price during night-time trading hours when the maximum permissible trade size is 60 lots, this error will occur.
Solution: To avoid this error, ensure that all trades adhere to the volume limits specified by Taurex. Check the contract specifications within the trading terminal and adjust Expert Advisor settings accordingly.