bid value

[patriciad1153]

I'm a new subscriber to Gixen (and Gixen mirror) but have had no joy at all so far. Each time I try to enter a bid a banner appears at the top of the page telling me that the bid cannot be accepted because either the item number or the bid amount is wrong.
Having double-checked the item number I assume I must be entering the amount in the wrong format. I have been entering e.g. 50GBP.
Can you please tell me where I am going wrong as I have already missed several coveted items?

[mario]

Please do not enter the currency - only the amount, e.g. 50 or 12.34

Currency is always currency of the listing, whatever it is.