The validation rule is not working properly check
AND(
ISPICKVAL(Proof_ID_Type__c, “PAN Number”),
OR(
LEN(Proof_ID_Value__c) <> 10,
NOT(
AND(
ISNUMBER(VALUE(MID(Proof_ID_Value__c, 6, 4))) = TRUE,
ISNUMBER(VALUE(MID(Proof_ID_Value__c, 1, 5))) = FALSE,
ISNUMBER(VALUE(MID(Proof_ID_Value__c, 10, 1))) = FALSE
)
)
)
)