Check your VAT codes under General Ledger/Maintenance/VAT.
Is the VAT rate set to 25%?
Is the VAT code set up as Gross or Net 'Calculation base' under your VAT 'Options'? That is to say, have you instructed Uniconta to calculate the VAT based on you entering a value before or after VAT?
If, for example, you wish to enter an amount of 10,000 EUR in a general journal and that Uniconta calculates 2,500 EUR as VAT, then you need to select 'Net amount' on the VAT set up. If, however, you would like to enter 10,000 EUR in the general journal (including VAT) and that Uniconta calculates VAT of 2,000 EUR, then you will need to select 'Gross amount' under 'Options' for your 'Calculation base'.