Getting error for IF expression

[Ravi Kanth Tadoori]

IF([entry.transactions]>10 && [entry.ListOfApps]>10, "Large", "Medium") 
||
IF([entry.transactions]<5 && [entry.ListOfApps]<5, "Small", "Medium") 

Im trying to achieve above expression in confiform field definition but getting "NA" , when entry.transactions and ListOfApps value is less than 5 whereas I'm expecting  Small

[Ravi Kanth Tadoori]

was able to use as below 

IF(
[entry.transactions] > 15 && [entry.listOfApps]> 15,
"Large",
IF([entry.transactions] < 5 && [entry.listOfApps]< 5,
"Medium",
"Small"
)
)